An Investigation of Photographic Phase Holograms

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Master's Theses Graduate College

8-1974

Dale Lance Markham

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Recommended Citation Markham, Dale Lance, "An Investigation of Photographic Phase Holograms" (1974). Master's Theses. 2607. https://scholarworks.wmich.edu/masters_theses/2607

This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. AS INVESTIGATION OP PHOTOGRAPHIC PHASE HOLOGRAMS

Dale Lance Markham

A Thesis Submitted to the Faculty of The Graduate College in partial fulfillment of the Degree of Master of Arts

Western Michigan University Kalamazoo, Michigan August, 1974

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS

Gratitude is expressed to ray Thesis Committee Members

Professors Nathan L. Nichols and John E. Herman for their

constructive criticisms which benefited in the writing of

this thesis. Particular thanks goes to my Major Thesis

Advisor Professor Stanley K. Derby for his time, patience,

and guidance given to me during the many months of this

investigation.

Dale Lance Markham

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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. M-6326 MASTERS THESIS MARKHAM, Dale Lance AN INVESTIGATION OF PHOTOGRAPHIC PHASE HOLOGRAMS. Western Michigan University, M.A., 1974 Physics, optics

Xerox University Microfilms ,Ann Arbor, Michigan 48106

THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OP CONTENTS

CHAPTER PAGE I THE PROBLEM AND ITS BACKGROUND...... q

II HOLOGRAPHY...... 3

III PROPERTIES OP PHASE HOLOGRAMS ...... n

IV EXPERIMENTAL ARRANGEMENT...... 17

Hologram Camera ...... q7

Transparency measurements ...... qa

V STUDIES IN BLEACHING PROCESSES ...... 22

Techniques for Producing Photographic Phase Holograms .... 22

The Modified Stanford Process ...... 24-

The Kodak Reversal Bleach System . . . 34

The Modified Developer Process .... 4 4

The Modified Reversal Bleach Process . 53

The Agfa P r o c e s s ...... 59

VI ATTEMPTS TO IMPROVE HOLOGRAPHIC IMAGES . . 66

Printout Resulting from Variable Light Intensities...... 55 Printout Resulting from Wavelength Variation of L i g h t ...... gg

Printout Resulting from Ultrasonic Agitation...... 7q

Ultrasonic Agitation Effect upon Wavelength Sensitivity ...... 72

Effects of Toners on Brightness and R e s o l u t i o n ...... 75

Liquid Gates and Holographic Resolution 76

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OP CONTENTS (Cont.)

CHAPTEN PAGE

VII SELECTING AN OPTIMUM HOLOGRAPHIC PROCESS . 78

CONCLUSIONS ...... g5

APPENDICES

I PROCESSING STEPS POE THE MODIFIED STANFORD P R O C E S S ...... S8

II PROCESSING STEPS FOR THE KODAK REVERSAL BLEACH SYSTEM ...... 99

III PROCESSING STEPS FOR THE MODIFIED DEVELOPER PROCESS ...... 100

IV PROCESSING STEPS FOR THE MODIFIED REVERSAL BLEACH PROCESS .... 101

V PROCESSING STEPS FOR THE AGFA PROCESS . . 102

VI PROCESSING STEPS FOR THE DERBY PROCESS . . 103

VII PROCESSING STEPS FOR THE MARKHAM PROCESS . 104

VIII INFORMATION ABOUT UNUSUAL CHEMICALS USED IN THIS PAPER ...... 105

FOOTNOTES ...... 108

BIBLIOGRAPHY...... H A

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST 0? TABLES

TABLE PAGE

1. Categorization of the Five Processes Investigated in this P a p e r ...... 26

2. The Essential Processing Steps of The Modified Stanford Process ...... 28

3» Pinal Absolute and Normalized Transparencies of Holograms Processed with The Modified Stanford Process and Processed with the Pour Modifications Performed on The Modified Stanford Process ...... 29

4. The Essential Processing Steps of The Kodak Reversal Bleach S y s t e m ...... 35

5. Pinal Absolute and Normalized Transparencies of Holograms Processed with The Kodak Reversal Bleach System and Processed with the Five Modifications Performed on The Kodak Reversal Bleach System ...... 4-3

6 . The Essential Processing Steps of The Modified Developer Process ...... 48

7. Pinal Absolute and Normalized Transparencies of Holograms Processed with The Modified Developer Process and Processed with the Three Modifications Performed on The Modified Developer P r o c e s s ...... 52

8 . The Essential Processing Steps of The Modified Reversal Bleach Process . . . 54

9. Final Absolute and Normalized Transparencies of Holograms Processed with The Modified Reversal Bleach Process and Processed with the Three Modifications Performed on The Modified Reversal Bleach Process . . . 55

10. The Essential Processing Steps of The Agfa P r o c e s s ...... 60

11. Pinal Absolute and Normalized Transparencies of Holograms Processed with The Agfa Process and Processed with the Pour Modifications Performed on The Agfa Process 61

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OP TABLES (Cont.)

TABLE p a g e

12. Summary of The Western Michigan University Modifications ...... 80

13. Final Absolute and Normalized Transparencies of Holograms Processed with The Twelve Western Michigan University Modifications 87

14. The Essential Processing Steps of The Derby P r o c e s s...... 91

15. The Essential Processing Steps of The Markham P r o c e s s ...... 92

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES

FIGURE P£G£

1. The Sand Box Unit ...... IS

2. Arrangement of Components in The Sand Box U n i t ...... 18

3. Arrangement of Transparency Measurement Zones on each H o l o g r a m...... is

4. Schematic of the Emulsion Cross Section for a Direct Bleach Process, a Negative Phase Image Process, and a Reversal Bleach Process ...... 25

5. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed without the prehardener in The Modified Stanford Process ...... 30

6. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed with D-76 substituted as the developer in The Modified Stanford Process 31

7. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed with potassium dichromate sub stituted as the bleaching agent in The Modified Stanford Process ...... 32

8. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed without the clearer in The Modified Stanford P r o c e s s ...... 33

9. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) and processed with D-19 substituted as the developer in The Kodak Reversal Bleach S y s t e m ...... 38

vii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES (Gont.)

FIGURE PAGE 10. Time Variation of Absolute and normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRB3) substituting D-19 and D-76 as developers 39

11. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 as the developer and substituting D-19 as the developer along with removal of the stain remover . • . 40

12. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 as the developer and substituting D-19 as the developer along with removal of the clearer ...... 41

13. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 as the developer and: 1) processed without the stain remover, 2) processed without the clearer, 3) processed without either the stain remover or the clearer ...... 42

14. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Developer Process (MDP) and processed with D-19 substituted as the developer in The Modified Developer Process 49

15. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Developer Process (MDP) substituting D-19 and D-76 as developers . 50 16. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Developer Process (MDP) substituting D-19 as the developer and substituting D-19 as the developer along with omission of potassium iodide from the bleach bath ...... 51

viii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES (Cont.)

FIGURE PAGE

17. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Reversal Bleach Process (MRBP) and processed with D-76 substituted as the developer in The Modified Reversal Bleach P r o c e s s ...... 55

18. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Reversal Bleach Process (MRBP) and processed with Sodium Bisulfite as the clearer in The Modified Reversal Bleach P r o c e s s ...... 57

19. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Reversal Bleach Process (MRBP) and processed without the clearer in The Modified Reversal Bleach Process . . . 58

20. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Agfa. Process (AP) and processed.with D-76 substituted as the developer in The Agfa Process ...... 62

21. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Agfa Process (AP) and processed without the clearer in The Agfa Pr o c e s s ...... 63

22. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Agfa Process (AP), processed without phenosafranine in the desensitizer of The Agfa Process, and processed without the desensitizer in The Agfa Process . . . 64-

23. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Developer Process arranged at various distances from a printout inducing light source ...... 67

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LI S3? OP FIGURES (Cont.)

FIGURE PAGE

24. Tine Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Reversal Bleach Process arranged at various distances from a printout inducing light source ...... 68

25. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Reversal Bleach Process arranged with different filters placed in front of a printout inducing light . . 70

26. Time Variation of Absolute and Normalized Transparency of Holograms processed with different modifications after agitation of the unexposed film in an ultrasonic c l e a n e r ...... 73

27. Wavelength Variation of the Darknesses of Spectral Lines on a Kodak S.A.-3 Spectro- graphic Plate Agitated in an Ultrasonic Cleaner before Exposure divided by the Darknesses of Spectral Lines on an Unagitated S.A.-3 Plate ...... 75

28. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications One and T w o ...... 29. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications Two and Three ...... q 2

30. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications Three and P o u r ...... 83

31. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications Five, Six, and S e v e n ...... 84

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. W'

LIST OP PIGUBES (Cont.)

PIGUBE PAGE

32. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications Six, Seven, and E i g h t ...... 85 33. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications Nine, Ten, Eleven, and Twelve ...... 86

34-. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications 4A, 12A, and 12B ...... 90

33. Time Variation versus Absolute Transparency for a Typical Bleached Hologram ...... 96

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER I

THE PROBLEM AND ITS BACKGROUND

Since the theory and research on holography was first 1 2 accomplished by Gabor , it was left to Leith and Upatnieks

to show that the idea of holography was more than just an

optical curiosity. The first holograms were recorded on

ultra fine grained photographic emulsions, processed with

just a development and a fixing stage. Cathey showed that

holograms could also be bleached resulting in an increased

brightness of the holographic image. Because a brightness

ratio of almost a factor of ten exists between bleached

and unbleached holograms, study proceeded in the direction

of developing better methods of producing bleached holo

grams. Other means of producing holograms such as recording

the hologram in dichromated gelatin or photoplastics have

been developed but because photographic emulsions are at

least 100 times faster than other materials and are sen

sitive to all wavelengths of visible light, most ventures

were turned towards photographic holography.

Along with the increase of brightness there are two

problems which must be solved before high quality bleached

holograms can be produced. The first problem concerns

the fact that a photographic emulsion, when bleached,

produces an excessive, amount of scattered light which

degrades the holographic image. A second problem concerns 1

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the fact that the final "bleached product is generally left

in the form of a silver halide, which exhibits printout

darkening as a function of time. As the silver halide

reduces hack into metallic silver, the hologram darkens

and the holographic information is lost. The resultant

increase in darkening of the emulsion is known as the

printout effect.

It is the purpose of this investigation to attempt

to produce bleached holograms which have good resolution

and high resistance to printout darkening.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER II

HOLOGRAPHY

Holography is a radically different concept in photo

graphic optics. The process, which can he called photog

raphy hy wavefront reconstruction, records the reflected

light waves from an object and not the image of the object,

being photographed, as with the normal photographic process

The photographic record, called a hologram, bears no

resemblance to the original object but contains in an

optical code all the information about the object that

would be contained in an ordinary photograph and much

additional information unrecordable by any other photo

graphic process. The hologram looks like a hodgepodge of

specks, blobs, and whorls upon the developed photographic

plate or film. The creation of an intelligible image from

the hologram is known as the reconstruction process, where

the waves optically recorded on the emulsion surface pro

ceed onward reconstructing an image of the original subject

oblivious to the time lapse in their history. These waves

are indistinguishable from the original waves and are

capable of all the phenomena that characterize the original

waves.

As in ordinary photography, the object is illuminated

and a photographic emulsion positioned to receive reflected

light from the object. However, no lens or other image 3

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. forming device is used in creating a hologram. Each point

on the emulsion receives light from the entire object;

conversely, each point on the object reflects light to

the entire photographic emulsion. The illuminating light

must be monochromatic and coherent, also different from

ordinary photography. Lastly, a mirror is used to direct

a portion of the coherent light directly to the plate,

bypassing the object. This beam is called the reference

beam, and it is the interference effect between it and

the reflected object light which creates the hologram.

The problem of wavefront reconstruction is to record

the exact form of the wave pattern reflected from an ex

tended and irregular object. To capture the wave pattern

completely both the amplitude and the phase of the waves

must be recorded at each point on the emulsion surface.

Ordinary photographic emulsions record wave amplitudes by

conversion of the amplitudes to corresponding variations

in the opacity of the emulsion. The emulsion, however,

is completely insensitive to phase relations. The technique

of interferometry is used in holography to preserve these

phase relations. It can be shown that relative phase infor

mation can be preserved in two-beam interference patterns.

The basic technique of hologram formation then is to divide

the coherent light coming from a laser into two beams; one

to illuminate the subject and one to act as a reference

beam. The reference beam usually has a spherical or planar

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. wavefront. The reference "beam is directed to intersect

the light reflected from the subject. Since these two

beams are coherent, an interference pattern will form in

the volume of space where the beams overlap. A photo

graphic emulsion placed in the overlap region thus records

the amplitude and phase relations from the reflected light

originating from the subject. After suitable processing

of the emulsion, the medium becomes the hologram.

The intensity of the interference pattern can be

regarded as a three-dimensional contour map. If the

photographic emulsion in the overlap region is very thin,

it will record line traces of the maximum intensity contour

surfaces. Such holograms are called plane holograms and

these holograms have properties similar to those of plane

diffraction gratings. If the photographic emulsion is

relatively thick, the contour surfaces themselves are

recorded. Such holograms are called volume holograms and

these take on properties of volume diffraction gratings.

A hologram made in the manner just described has many of

the properties of a grating made by a ruling engine; how

ever, such a grating has precise uniformity whereas a

hologram has complete nonuniformity. The inadvertently

produced irregularities in an imperfectly ruled grating

produces false spectral lines called ghosts, while the

deliberately induced irregularities in a hologram give

rise in the reconstruction process to a complete well

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. defined image.

The lines of developed silver on plane holograms and

the surfaces of developed silver on volume holograms are

very closely spaced and therefore diffract light signif

icantly. When the hologram is illuminated by the original

reference beam, part of the light diffracted out of the

reference beam is directed and shaped by the hologram into

a re-creation of the light wavefronts originally coming

from the subject. A reconstructed wave train proceeds

out from the hologram exactly as did the original subject

wave. An observer viewing a wave identical with the orig

inal subject wave perceives it to diverge from a virtual

image of the subject located precisely at the original

subject position. If the reference beam is accurately

positioned so that all rays of the reflected beam are

opposite to the original reference beam, then a real image

of the subject at the original subject location is produced.

Because the light converges to the image it can be directly

detected with a photographic emulsion without need for a

lens. In summary, a hologram acts as a combination rec

ording and projection system which provides an image of

the original subject when illuminated by the reference and

does so without the need for additional lenses.

Holograms and the images they produce have many cu

rious and fascinating properties. The pertinent infor

mation recorded on the hologram can be seen only under

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7 magnification and consists of highly irregular fringes

which hear no apparent relation to the subject. A hologram

can he broken into small fragments and each fragment will

produce a complete image. However, as the pieces get

smaller, the image resolution is lost. The hologram is

itself a positive, not a negative. Normally one would

consider a hologram as a negative, but the image it pro

duces is a positive. The photographic emulsion containing

the hologram registers only two levels of density; trans

parent and opaque. However, the tonal qualities of the

image do not suffer. Several images can be superimposed

on a single emulsion with successive exposures, and each

image can be recovered without being affected by the other

images. The virtual image is seen by looking through the

hologram as if it were a window-. The image appears in

complete three-dimensional form. As the observer changes

his viewing position the perspective of the picture changes,

just as if the observer were viewing the original scene.

Parallax effects are evident between near and far objects.

If an object in the foreground lies in front of something

else, the observer can move his head and look around the

obstructing object to see the previously hidden object.

One must refocus his eyes when the observation is changed

from a near to a far object. In short, there are no visual

tests one can make to differentiate the image from the

real object. The real image will hang in space between

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the observer and the hologram also having all of the above

mentioned features; however, this real image is much more

difficult to view.

The light used to illuminate the object must be both

coherent and monochromatic. If the spectrum of the light

was broad, each wavelength component would produce its own

separate pattern and the resultant of all these components

would average out the fringes and produce a smooth dis

tribution. Thus the requirement for a monochromatic source.

If the source is non-coherent, then each source element

produces interference fringes displaced from those of other

elements; thus, the sum of many such sets of fringes aver

ages to some very nearly uniform value, thus losing the

desired fringe pattern.

Holography was intended as a tool for electron micros

copy. It occurred to Gabor in 194S that the aberrated

image produced by an electron lens still preserves all of

the subject information but in a somewhat coded form. If

the aberrated image could somehow be decoded, the reso

lution limit of the electron microscope perhaps could be

increased by a factor of ten. Gabor dispensed with the

microscope altogether and performed a decoding operation

on a photographic record of unfocused electron waves

diffracted from the subject. He theorized that this wave

record could be decoded by illuminating it with coherent

visible light; thus, waves arising out of the diffraction

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. yield the optical equivalent of the unfocused electron

waves* These waves should yield a highly magnified optical

image, the magnification being given by the ratio of the

light wavelength to that of the electron wavelength. The

light beam must be an accurately scaled imitation of the

electron waves. Gabor formed the first hologram with

visible light to test his theory. At that time, and even

now, it is not possible to obtain the required beam coher

ence in an electron wave and difficulties also exist in

high resolution recording at very short wavelengths.

Before the invention of the laser, the concept de

rived by Gabor seemed to be doomed to a class of optical

curiosities. Due to the many obstacles, little progress

was made and the concept abandoned for nearly a decade.

However, in the early 1960's Leith and TJpatnieks^ bright

ened prospects in holography, by employing the newly

developed laser which provided a very intense, monochro

matic, coherent light source. By 1964 they had convincing

proof that holography was indeed practical. This was a

long step from Gabor's idea of wavefront reconstruction.

Several imaginative applications seem to rest in the

balance if holography can be improved. One specific appli

cation seems to lie in the areas of electron or x-ray

holography as first proposed by Gabor. Holograms recorded

in these electromagnetic frequencies may theoretically be

reconstructed in visible light. The most sensational

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10

future application of holography undoubtedly lies in the

field of producing three-dimensional television and motion

pictures; however, technical problems must be surmounted

before these forms of entertainment become a reality.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER III

PROPERTIES OP PHASE HOLOGRAMS

In optical holography a photographic emulsion is used

to record the sum of the wavefronts from the object and

from a reference beam, the reference beam making possible

the recording of both the amplitude and the phase of the

object wavefront. The amplitude of the object wavefront

is represented by the intensity of a fringe pattern re

corded by the density of developed silver sites while the

phase of the object wavefront produces variations in the

position of the fringes. The resulting holographic image

is due in part to the different amplitudes of metallic

silver developed on the photographic emulsion. Such a

hologram is sometimes called an amplitude hologram, since

in reconstruction of the image, the photographic emulsion

spatially amplitude modulates the wavefront of the illumi

nating beam in a way to reconstruct the original wavefront

from the object.

Analogous to a modulated carrier in electrical commu- 5 nications, Cathey first developed the idea that spatial

phase modulation could replace spatial amplitude modulation

in reconstruction of the holographic image. If an amplitude

hologram is bleached, so as to convert the metallic silver

to a transparent compound whose index of refraction differs

from that of the gelatin, then the holographic record is 11

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 12 written in the resulting localized changes in the index

of refraction of the emulsion. Such a hologram is some

times called a phase hologram, because the holographic

information is now due to a spatially phase modulated

wavefront•

Since Cathey^ first bleached a photographic plate

and showed that phase holograms add more flexibility to

the wavefront reconstruction process, other methods of

producing pure phase holograms have been developed.

Materials other than bleached photographic emulsions for

producing phase holograms include: dichromated gelatin^”11)

photopolymer thick thermoplastics^^*1^ , photo

resist (-*-9-24), iron o x i d e ^ * 2^ , photoplastics^2^-2^ .

Two terms are useful in describing properties of

holograms: these are diffraction efficiency and signal to

noise ratio. These terms may be applied equally well to

either amplitude or phase holograms. The brightness of

a holographic image can be described by the term diffrac

tion efficiency which is defined as the amount of light

diffracted by the hologram into making the holographic

image, divided by the incident light upon the hologram.

Diffraction efficiency is usually expressed as a percentage.

The resolution of a holographic image can be described by

the term signal to noise ratio, which is defined as the

ratio of the intensity of the diffracted light originating

from the object as compared to the intensity of the scat—

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 13 tered light originating from the background.

Holograms suitably processed in dichromated gelatin^

have diffraction efficiencies of as high as 90% and signal

to noise ratios of 230 to 1. These holograms have good

environmental stability but their spectral sensitivity

is limited to the short wavelengths. Holograms suitably

processed in photopolymer materials^ have diffraction

efficiencies of as high as 80% and signal to noise ratios

of 200 to 1 but the environmental stability of photopolymer

materials must be improved. Holograms suitably processed 32 in thick thermoplastics have diffraction efficiencies of

25% and signal to noise ratios of 70 to 1 but the material

distorts at high temperature and humidity and is not very

sensitive at long wavelengths. Holograms suitably processed

in photoresist materials^ have diffraction efficiencies

of 80% and signal to noise ratios of 250 to 1 but humidity

causes fine cracks to form in the photoresist material. 34- Holograms suitably processed in iron oxide materials have

excellent stability against all environmental parameters

but the maximum diffraction efficiencies are 20% and signal

to noise ratios 15 to 1. Holograms suitably processed in

photoplastics^ have good environmental stability and

sensitivity at long wavelengths but diffraction efficiencies

of only 10% and signal to noise ratios of 45 to 1 have been

reported. Burckhardt^ has shown that theoretically it is

possible to produce bleached photographic holograms with

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 14

1 0 0 % diffraction efficiency, whereas the maximum possible

diffraction efficiency of unbleached photographic holograms

is about 4%. Latta^, and Upatnieks and Leonard^ 8 have

produced bleached photographic holograms with diffraction

efficiencies of about 60%.

Because of their high sensitivity to light, especially

at long wavelengths, photographic emulsions are still

preferred for recording holograms. When a photographic

emulsion is developed, fixed, and then bleached, the plate

or film is rendered almost transparent. Because of reduced

attenuation of light, spatial phase modulation methods are

capable of producing a brighter image than spatial ampli

tude modulations.

The phase modifications to the incident beam can be

caused by an index of refraction variation in the emulsion

or by relief images on the emulsion surface. Variation of

the index of refraction is proportional to the mass of

silver originally exposed, thus the more silver sites

originally exposed and converted to a transparent material,

the greater the change in the index of refraction. Since

the mass of silver is proportional to the silver density,

holograms which demonstrate high diffraction efficiencies

when bleached have high original densities. Variation in

the relief image height is also proportional to the orig

inal silver density as well as dependent on the tanning

action produced on the gelatin by the developer and the

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 15 ■bleach. Tanning is the result of a higher than normal

degree of cross linking of the gelatin molecules due to

chemical treatment of the emulsion. Tanning causes the

gelatin layer to become insoluble in water. Upon drying,

that area of the gelatin receiving a greater degree of

tanning becomes thicker than the less tanned area because

the amount of water absorption, and hence the volume

expansion, decreases with increased tanning.

Unfortunately, while bleached photographic holograms

have high diffraction efficiencies, the improved efficiency

is accompanied by an increase in scattered light reducing

the image resolution. Also, the materials remaining in

the emulsion are very prone to convert back into metallic

silver (printout effect), rendering the hologram darker

and the holographic image of lesser quality. Several

reasons have been proposed for the poor resolution quality

of a bleached holographic image: local changes in emulsion

thickness on development due to release of stress intro

duced by factory drying, tanning of the emulsion by the

developer and bleach, stress formation during the drying

of the emulsion, silver being extruded from geometrically

regular positions to filamentary tangles in developing,

scattering by the large silver halide grains, optical

irregularities or phase errors within the volume of the

emulsion, localized lateral distortions that vary according

to the grain pattern of the signal beam.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 16

All of the above factors are contributors to the

scattering of light in bleached holograms which is clas

sified as optical noise. Methods of controlling the

printout effect as well as lowering the optical noise

in photographic phase holograms must be found before an

optimum process can be reported.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER IV

EXPERIMENTAL ARRANGEMENT

Hologram Camera

The holograms were exposed in a hologram camera known

as a "sand "box unit". The unit is so named because the

laser and the lenses and mirrors which diverge and reflect

the laser beams are simply placed into a box full of sand.

The box is a table turned upside down which has a retaining

wall of six inch depth which is filled with sand. The box

is placed upon a truck tire inner tube which is not fully

inflated. The tube in turn lies on another table which

isolates the system from the floor and walls. The tube

is not fully inflated to better act as a vibration damper.

The box is isolated from the floor and walls to prevent

vibrations from entering the system. The laser, lenses,

and mirrors are placed in the sand as a further precaution

against vibration (figure 1 ).

The components of the hologram camera were arranged

as in figure 2. The laser was a Bausch and Lomb He-Ne

Gas L aser^ which produced a beam of 0.6 milliwatts full

intensity at 6328 angstroms. A black box was positioned

over the laser with only a hole to let the beam out in

order to cut out the background glare produced by the laser.

The reference beam to stage illumination ratio was 1.5 to

1, and the angle between these beams was 60 degrees. The 17

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Components

/1 \ Inverted ‘ Table Sand'

Retaining Wall 2^ Inner Tube — T 7 \ -Table

Figure 1. The Sand Box Unit

Plane ^ \ ^ Plane Mirror Mirror Microscope Lenses \L

Beam Splitter

Film ^Platform

Figure 2. Arrangement of Components in The Sand Box Unit

One-Eighth Hologram Inch Circles

Figure 3. Arrangement of Transparency Measurement Zones on each Hologram

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19

stage consisted of a series of spikes for estimating

signal to noise ratio of the holographic image as well

as the backside of a Kennedy half dollar for determining

the resolution properties of the image.

The hologram box was placed in a photographic darkroom

where no light or air currents could enter. To expose a

hologram a black piece of cardboard was placed in front

of the laser beam, the unexposed film was positioned by

means of clips onto the film platform, the system was

allowed to rest for thirty seconds so that vibrations

were damped out, then the cardboard was carefully raised

to allow the beam to enter the system. After the proper

exposure time the cardboard was lowered blocking off the

beam and ending the exposure. The hologram was then proc

essed immediately in a separate darkroom.

Transparency Measurements

The method of determining the transparency of holo

grams was straightforward and simple. After the hologram

was processed, five circles one-eighth inch in diameter

were drawn on the non-gelatin side of the hologram (fig

ure 3). Each small circle of the hologram was then 40 oriented in turn in a Bausch and Lomb Microphotometer

and the transparency of the small circular area was

measured. The working value for each hologram transpar

ency was taken as the average of the five values recorded

for the five circular areas. The holograms were then

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 20 placed on a light box of diffused fluorescent light

(intensity 145 foot-candles) for twenty-four hours a day.

Any evidence of printout darkening could be detected if

after a given period of time a further check of the

holographic transparency showed changes, the assumption

being that the changing transparency of the hologram is

directly related to the phenomenon of printout darkening.

Duplicate holograms were generated for each modi

fication of the various parameters of developing, bleaching,

clearing, and desensitization. Each duplicate hologram

pair resulted in printout versus time curves that were

very similar. Because of this similarity, the duplicate

measurements for each pair were averaged and plotted as

a single curve.

The absolute percentage of transmitted light was

plotted as a function of time to determine the transparency

variation of each modification. The higher the transpar

ency of the modification, the more likely it is for the

hologram to have a high diffraction efficiency. The

normalized percentage of transmitted light was plotted to

determine the printout variation of each modification as

a function of time. The lower the printout resistance

of the modification, the more likely it is for the holo

graphic image to suffer a degradation. The absolute

percentage of transmitted light is read directly from the

microphotometer. The normalized percentage of transmitted

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 21

light is found by dividing the holographic transparency

as a function of time by the initial holographic trans

parency .

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER Y

STUDIES IN BLEACHING PROCESSES

Techniques for Producing Photographic Phase Holograms

A search was made in the literature for ways of

producing high quality photographic phase holograms. It

was found that several groups had evolved their own

particular means of processing. Of these processes, each

can be placed into one of three categories for production

of photographic phase holograms. These categories are:

1 ) direct bleaching process, 2 ) negative phase image

process, 3 ) reversal bleaching process.

In a typical direct bleaching process the emulsion

is developed and fixed, then bleached in a solution that

converts the metallic silver into a transparent, insoluble

salt having a refractive index significantly higher than

that of the gelatin. When the emulsion dries, a relief

image is formed where the developer converts the silver

halide into metallic silver. The tanning tends to be

fairly localized within the emulsion and as a result the

emulsion pulls together. Por a direct bleaching process

the variations of optical path length from the relief image

and those from index variations within the emulsion are

additive, consequently excessive optical noise is produced

upon the reconstructed image. 22

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23 In a typical negative phase image process, the exposed

emulsion is developed but not fixed so that silver halide

remains in the unexposed regions. The emulsion is then

bleached in a suitable bleach bath which converts the

metallic silver to a soluble salt and removes it from the

emulsion. Because the remaining silver halide appears as

a negative for a direct process, this is referred to as a

negative phase image process. In a direct bleach process

the formed relief image enhances scattered light. However,

the negative phase image process keeps the relief image

path length variation of light to a minimum. This dras

tically reduces the optical noise in the holographic image.

Maximum tanning occurs in regions of maximum development

and thus there is a tendency for a relief image to be

formed at the position of the silver sites. However, the

bulk of the silver halide tends to counteract this effect

and for commonly used developers this bulking seems to be

the stronger effect.

In a typical reversal bleach process the exposure

and development of the hologram are carried out to form

a normal silver image. The hologram is then re-exposed

to a uniform source of white light making developable the

silver halide grains not protected by the previously

formed silver image. The hologram is bleached after the

second development, thus the metallic silver formed in

either development is removed leaving a phase image formed

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. only from the residual silver halide. If the second

exposure is controlled, almost the entire "background of

silver halide grains can be eliminated leaving a phase

image consisting of the silver halide grains shielded by

the silver formed from the first exposure. It is intu

itively obvious that reduction of this background would

reduce the scattered light inherent in a bleached holo

graphic image. Figure 4 shows schematically the three

previously described processes.

Of the processes described in the literature five

were selected for investigation in this paper because of

the claims that each processed holograms of high diffrac

tion efficiencies, high signal to noise ratios, and high

resistance to printout. These processes were: 1) The hi Modified Stanford Process , 2) The Kodak Reversal Bleach

System^2, 3) The Modified Developer Process^, 4) The 44 \ 45 Modified Reversal Bleach Process , 5) The Agfa Process •

The following experimental work is directed towards exam

ining each process in detail and combining the good fea

tures of these five methods into an optimum process for

creating photographic phase holograms. Table I categorizes

each process investigated in this paper.

The Modified Stanford Process

The Modified Stanford Process is a result of modifi

cations on The Stanford Process. The Stanford Process was

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

VJ1

remove Ag light uniformwhite 5) 5) Bleach to 3) 3) Re-expose with 2) 2) Develop 4) 4) Redevelop 1) 1) Expose

AgBr yigBr I I Base I Ag

AgBr AgB

remove Ag represent emulsion movement) 2) 2) Develop 3) No Fix 1) 1) Expose 5) 5) Dry (Arrows 4) 4) Bleach to I- Baae I I- LBase I c w i AgBr-^ AgBr AgBr

to a silver convert Ag emulsion represent halide movement) a Negative Phase Image Prooess, and a Reversal Bleach Process 1) 1) Expose 2) 2) Develop 3) 3) Fix 5) 5) Dry (Arrows 4) 4) Bleach to _ Baas I Figure 4. Schematic of the Emulsion Cross Section for a Direct Bleach Process, I BaseI I L,., Direct Bleach Process Negative Phase Image Process Reversal Bleach Process ;— :Br— V Ag^CDD AgBr Ag- Ag- AgBr' Silver Silver Halide Halide

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 26 Table I

Categorization of the Five Processes Investigated in this Paper

Modified Stanford - Direct Bleach Process

Kodak Reversal Bleach - Negative Phase Image Process

Modified Developer - Negative Phase Image Process

Modified Reversal Bleach - Reversal Bleach Process

Agfa - Negative Phase Image Process

46 developed by Lehmann, Lauer, and Goodman at Stanford

University. To negate the effects of the relief image

formation in a direct bleaching process they introduced a

prehardening step immediately after exposure and before 47 development. Lehmann, Lauer, and Goodman report that

the speed of Agfa films decreases in proportion to the

prehardening time. However, as the prehardening time

increases the diffraction efficiency and signal to noise 48 ratio both decrease. Upatnieks and Leonard report that

Kodak Prehardener SH—5 reduces the relief pattern and

localized distortions on Kodak 649-F plates giving better

diffraction efficiency and signal to noise ratio. The

Stanford Process utilizes cupric bromide as a bleaching

agent. Lehmann, Lauer, and Goodman^ theorize that the

bleach first converts the metallic silver to silver bromide

leaving insoluble cuprous bromide in the emulsion. A

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 27

clearing bath consisting of a mixture of potassium perman

ganate and potassium bromide then converts the cuprous

bromide back into soluble cupric bromide and also removes

the sensitizing impurities from the emulsion leaving a

transparent silver bromide medium of refractive index 2 . 2 5

in the emulsion. In regard to printout behavior, Lehmann, 50 lauer, and Goodman only reported that holograms exposed

to rooms lighted by fluorescent lights, sunlight filtered

through Venetian blinds, and scanned by a He-Ne and Argon

lasers yielded after seventy days no appreciable evidence

of printout. Since the final emulsion product is silver

bromide, one would expect that a printout would occur

fairly rapidly as a function of time, as reported by 51 McMahon and Maloney .

The Stanford Process was modified by Colburn, Zech,

and Ralston^ 2 in two ways: 1) an amount of ferric chloride

equal to that of the cupric bromide was added to the bleach,

2 ) a two step drying process of 5 0 % methanol then 1 0 0 %

methanol was instituted to insure a more uniform and quicker

drying procedure as well as helping clear the emulsion

surface of sensitizing impurities. This modified process

they named The Modified Stanford Process. The essential

processing steps of The Modified Stanford Process are given

in Table II. Holograms processed by The Modified Stanford Process

gave brighter holographic images than with any other process

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table II

The Essential Processing Steps of The Modified Stanford Process

Step 1 ...... Preharden in Kodak SH-5

Step... 2 ...... Develop in Kodak D-19

Step 3 ...... Fix in Kodak fiapid Fixer

Step 4 ...... Bleach in Ferric Chloride and Cupric Bromide

Step 5 ...... Clear and Desensitize in Potassium Permanganate and Potassium Bromide

tried in this paper. However, image resolution was not

as good as with most of the processes, indicating much

scattering of light in the emulsion due either to the

"bleaching process or to the relief image formed by such

a direct bleaching process. No qualitative data were

taken on diffraction efficiency or signal to noise ratio.

The printout effect was studied in a much more qual

itative manner. The Modified Stanford Process was further

altered in this investigation by the omission or substi

tution of a certain processing step to better understand

how each step changes the printout resistance of the

emulsion. The first variation of The Modified Stanford

Process involved omission of the prehardening step. The

second change was the replacement of D-19 with D-76 as

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. the developer. The third change was the substitution of

potassium dichromate as the bleaching agent. Variation

number four was the omission of the clearing bath.

Figures 5-8 illustrate the transparency response of

the bleached emulsions to the alterations of The Modified

Stanford Process while Table III gives the final absolute

and normalized transparencies of these alterations.

Table III

Final Absolute and Normalized Transparencies of Holograms Processed with The Modified Stanford Process and Processed with the Four Modifications Performed on The Modified Stanford Process

Absolute Normalized Transparency Transparency

Modified Stanford Process 45% 1 1 0 %

Without Prehardener 52% 105%

Developed with D-76 52% 96%

Bleached with Potassium Dichromate 8 6 % 99%

Without Clearer 33% 89%

Figures 5-8 show that although printout is extreme

in all modifications within the first week, each modifi

cation recovered as time progressed. Although all proc

esses leveled off to a constant transparency after a ten

week period, some of the modifications have final trans

parencies above those of the initial readings. Processing

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 0

50 +» axi kDkO 45 ca-H •p^ n ©*o o © 40 Ft+> © 43 O Reference, (MSP) B © © 35 •P C Processed without 3 gj A H the prehardener Ofrt © 30 ,0«H ■< O 25 10 Time in Weeks

120

■Or) © a N © § 80

O S5 O

10 Time in Weeks

Figure 5. Time Variation-of Absolute and normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed without the prehardener in The Modified Stanford Process

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55

O Reference, (MSP) A Developed with D-76

10 Time in Weeks

12CT

k T3 O © Ph -P +> TJ *h © S 63 © 8C

2 4 6 8 10 Time in Weeks

Figure 6. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed with D-76 substituted as the developer in The Modified Stanford Process

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 32

80 O Reference, (MSP) A Bleached with potassium dichromate ® 'O o © h+» o) -p & -H s © ®

iH OH 40

10 Time in Weeks 110

£h xf © © p-t -p

•O -H 8 0 ® e ea m Jh § 70 3$ a 64 S o 60

10 Time in Weeks

Figure 7• Time Variation of Absolute and normalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed with potassium dichromate sub stituted as the bleaching agent in The Modified Stanford Process

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 45 O Reference, (MSP) -p © X A Processed without ce-H 40 ■p-3 the clearer c © ■© o © ft -P 35 © -P P4 -H S © © ■P c 30 3 0} «—I F( o c-t m &

110 n

50 1 _L JL 4 5 6 8 10 Time in Weeks

Figure 8. Time Variation of Absolute and Formalized Transparency of Holograms processed with The Modified Stanford Process (MSP) and processed without the clearer in The Modified Stanford Process

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34

without the prehardener yields a higher transparency than

processing with the prehardener; however, probably with

decreased diffraction efficiency and signal to noise ratio

although no measurements were taken. Developing in D-76

yields holograms which are more transparent but more apt

to printout than holograms developed in D-19. Holograms

bleached with potassium dichromate are almost completely

transparent; however, the holographic image is very faint

indicating perhaps that potassium dichromate is not a

suitable agent for holograms processed with a direct

bleach process. Holograms processed without being cleared

were very low in both transparency and printout resistance

indicating that the potassium permanganate and potassium

bromide in the clearer increase the holographic trans

parency as well as desensitize the hologram to printout.

The shape of the curves in Figures 5-8 would seem to

indicate that the recovery rates of the curves are inde

pendent of any change made in this investigation. Perhaps

the sudden printout and gradual recovery is normal to a

direct bleach process. Further investigations will be made in this paper to attempt to better understand the

behavior of this transparency response.

The Kodak Reversal Bleach System

The. Kodak Reversal Bleach System which was developed

by Lamberts and Kurtz*^ utilizes a special developer which

produces sufficient tanning action to keep the relief image

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 35 path length variation to a minimum, which is the primary

function of a negative phase image process. The essential

processing steps of The Kodak Reversal Bleach System are

given in Table IV.

Table IV

The Essential Processing Steps of the Kodak Reversal Bleach System

Step 1 . ,

Step 2 . . Potassium Dichromate

Step 3 . . Potassium Permanganate

Step 4 . . Sodium Bisulfite

The active constituent of Kodak Special Developer 5 h. SD-48 is pyrocatechol , which provides a strong tanning

action with its high value of pH. The relief image is

formed because of the strong local tanning action of the

special developer on the gelatin in regions where devel

opment to metallic silver takes place. This tanning

action causes the gelatin to pull together when drying,

increasing the thickness of the emulsion layer relative

to other areas. The refractive index variation of the

gelatin occurs because the developed silver is removed

from the gelatin by the bleach which results in a higher

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. concentration of the original high index silver halide

crystals in regions that received less exposure, and thus,

an increase in the refractive index of the emulsion layer.

Lamberts and Kurtz^ reported a diffraction effi

ciency of 46% and a signal to noise ratio of 17 when the

process was used on Kodak 649-? plates. No mention was

made of possible printout darkening.

Pyrocatechol is a hazardous material and when using

the developer caution is needed. Rubber gloves seemed

unsuitable since several gloves developed leaks after

contact with the developer; however, plastic gloves worked

very well. The developing stage of this process was very

difficult to control. With the Agfa 10E70^^ film a devel

opment time of two minutes was found to give optimum

results as to the holographic image. The images obtained

were not of particularly high efficiency but the reso

lution of the images was good. One would expect a high

tanning developer such as pyrocatechol to have less of

a relief image forming effect on a thin emulsion such as

Agfa 10E70 film (about 5 microns) than on a thick emulsion

such as Kodak 649-F^ plates (about 18 microns). Thus a

smaller diffraction efficiency and smaller signal to noise

ratio might be expected with Agfa 10E70 film, although

no qualitative data were taken. The printout effect was studied in a much more qual

itative manner. The Kodak Reversal Bleach System was

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37

further modified in this investigation by the omission or

substitution of a certain processing step to better under

stand how each step changes the printout resistance and

transparency of the emulsion. The first variation of The

Kodak Reversal Bleach System was the replacement of the

special developer with D-19. The second variation was

the replacement of the special developer with D-76. The

third variation was the omission of the stain remover.

The fourth variation was the omission of the clearer.

The fifth variation was the omission of both the stain

remover and the clearer.

Figures 9-13 illustrate the transparency response

of the bleached emulsions to the alterations of The Kodak

Reversal Bleach System while Table V gives the final

absolute and normalized transparencies of these alter

ations.

Developing the hologram with the special developer,

with D-19» or with D-76 produces transparency and print

out behavior responses which are almost indistinguishable.

Holograms processed without the stain remover were un

changed in transparency from holograms processed utilizing

the stain remover; however, the printout was noticeably

less extreme indicating that the potassium permanganate

which is the working agent in the stain remover tends to

speed printout darkening in the emulsion. Holograms

processed without the clearer were much less transparent

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced

Normalized Percentage Absolute Percentage Figure 9- Time Variation of Absolute and ofand Normalized Absolute TimeVariation 9-Figure of Transmitted Light of Transmitted Light 40 80 65 60 90 r 90 n 0 1 0 and and (KBBS) System TheBleach Kodak Reversal with processed of Transparency Holograms developer in The Kodak Reversal Bleach System Bleach Reversal developer Kodak Thein 1 processed with D—19 substituted as the assubstituted D—19 processedwith 2 2 3 3 A O Reference, D-19 developed D-19 Reference, O Time inWeeks Time Time in Timein Weeks 4 oa eeslBec System Bleach Reversal Kodak 5 5 6 6 (KKBS) 7 7 8 8

9 9

10 10

O Reference, Developed in D-19

A Developed in D-76

40 0 1 4 62 8 10 Time in Weeks

0) W-P 85 aJ si -p *0 C -H o o 80 © © Ph -P -P 'O -H 75 © S N © - h q H 0$ 70 <3 U g * O V t a o 65

60 XX X 4 5 6 8 10 Time in Weeks

Figure 10, Time Variation of Absolute and Formalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 and D-76 as developers

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65 i-, •p © J2 ui u - _ _

~~0 4 5 6 8 10 Time in Weeks~~

~~© W-P 85 aS jS - p W C - H © o 80 Ft *a © © P4-P -p TJ -H 75 © g N © £ 70 as h S eh u o~~

~~60 _L ± ± 4 5 6 8 10 Time in Weeks~~

Figure 11. Time Variation of Absolute and normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 as the developer and substituting D-19 as the developer along with removal of the stain remover

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 1 7 0 1- O Reference, Developed in D-19 +» ® x i low aJ-H 60 A Developed in D-19 and processed 4* Id without the clearer © T3 o © 50 - Jh -P © + » P4-H a © © -p c 40 “ 2 gS rH fl O £4 © .0*4 30 < O 20 XX X X 0 4 5 6 7 8 10 Time in Weeks

~~100~~

~~© W-P 90 CSX! - P W d -H © id o 80 © © 034 +» -P 'O t4 70 © a n m § as d 60 g * o *4 55 o 50~~

~~40 _L X X X 4 5 6 7 8 10 Time in Weeks~~

Figure 12. Time Variation of Absolute and Normalized Transparency of Holograms processed with The Kodak Reversal Bleach System (KRBS) substituting D-19 as the developer and substituting D-19 as the developer along with removal of the clearer

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. if S ^ ^ 7 ! V ■’ J ^ 1'- . ^ ,•■*-■'' '''-** \T- ■, ’ <(”??, '■ J - »*L '' ■ .* ■■-'■■ .. . ,- _ •■■_. . ,\~ *-S : , - : C ■ ■ .‘"T1'. ' ,'^v^V ■*■..■ V '- ■ .■ *. '■*<_ . ‘‘t- ,-■'

60 O Ho stain remover ■p OSS V k O 50 A Ho c le a re r aS *H •Pt-3 C © T3 lO Ho stain remover or clearer O © Ft -P 40 © -P P*-H S © 03 30 •P C 3 aJ rl F» O ^ © 2 0 <: o 10 XXX 0 4 - 5 6 8 10 Time in Weeks

~~1 0 0 i—,~~

~~© W-P 90 as - P w ©C -H»-3 O 80 Ft >© © © Ph +> -P 'CJ -H 70 © S 63 © ■H £ i—i as as Ft 60 I 51 O VH S5 o 50~~

~~40 X I ^ -3 4 5 6 8 10 Time in Weeks~~

Figure 13. Time Variation of Absolute and normalized Transparency of Holograms processed with. The Kodak Reversal Bleach System (KBBS) substituting D-19 as the developer and: 1) processed without the stain remover, 2) processed without the clearer, 3) processed without either the stain remover or the clearer

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 43 Table V~~

~~Final Absolute and Normalized Transparencies of Holograms Processed with The Kodak Reversal Bleach System and Processed with the Five Modifications Performed on The Kodak Reversal Bleach System~~

~~Absolute Normalized Transparency Transparency~~

~~Kodak Reversal Bleach System 40% 66 %~~

~~Developed with D-19 42% 65%~~

~~Developed with D-76 38% 64%~~

~~Without Stain Remover 39% 74%~~

~~Without Clearer 28%------47%----~~

~~Without either Stain Remover or Clearer 32% 67%~~

~~and much more susceptible to printout than holograms~~

~~processed utilizing the clearer. This indicates that~~

~~sodium bisulfite which is the working agent in the clearer~~

~~is an important chemical in retaining high transparency~~

~~and high resistance to printout in The Kodak Reversal~~

~~Bleach System. Transparency and printout are moderate~~

~~with holograms processed without either the clearer or~~

~~the stain remover. This is reasonable since processing~~

~~without the clearer yields holograms very susceptible to~~

~~printout and low transparency while processing without~~

~~the stain remover yields holograms which have the opposite~~

~~qualities as those just mentioned. The quality of the~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 4~~

~~holographic images was not noticeably different with any~~

~~of the above mentioned alterations, although no qualitative~~

~~data were taken.~~

~~The Kodak Reversal Bleach System is not particularly~~

~~impressive as far as printout behavior is concerned. Since~~

~~Agfa 10E70 emulsions are thinner than Kodak 649-F plates,~~

~~the tanning action of the developer used in this process~~

~~probably is not as effective as could be hoped for with~~

~~thicker emulsions. Although the process shows a 31%~~

~~decrease in transparency over a period of ten weeks indi~~

~~cating that the printout effect is a problem in this~~

~~process, it was found that sodium bisulfite is a useful~~

~~chemical in curtailment of the printout effect.~~

~~The Modified Developer Process~~

~~The third process studied was that of Hariharan, 58 Kaushik, and Hamanathan . This process, which has as~~

~~its special property a modified developer, will be called~~

~~in this paper The Modified Developer Process. This process~~

~~is a result of modifications of The Kodak R-10 Bleach 5Q Process which was first used by Altman*^* and later by~~

~~Russo and Sottini6®, McMahon and Franklin63*, TJpatnieks and~~

~~Leonard6^, and McMahon and Maloney6^. The initial R-10~~

~~Bleach Process utilized sodium chloride to change the~~

~~final developed silver image into a silver chloride com-~~

~~plex; however, McMahon and Franklin as well as TJpatnieks~~

~~and Leonard6 *5 reported that R-10 Bleaches belong to a class~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. of printout enhancing materials- It was left to McMahon 66 and Maloney to show with qualitative data that the

~~stability against printout is essentially determined by~~

~~the silver halide of which the image is formed, silver~~

~~chloride being the poorest, silver bromide being somewhat~~

~~better, silver iodide being the best, exhibiting a high 67 resistance to printout darkening- McMahon and Maloney~~

~~thus modified The Kodak R-10 Bleach Process to incor~~

~~porate a potassium iodide solution in order to change~~

~~the final image into a silver iodide.~~

~~The modified process worked fine with thin emulsion~~

~~Agfa materials but poor results as far as image formation~~

~~was concerned were obtained when the process was used on go thicker Kodak 649-F plates. Hariharan and Eamanathan~~

~~theorized that since silver iodide has a relatively high~~

~~solubility in solutions of potassium iodide the solvent~~

~~action of potassium iodide could result in etching of the~~

~~halide image and loss of the high spatial frequency inter~~

~~ference pattern inherent in the hologram. By lowering~~

~~the concentration of potassium iodide in the bleach bath,~~

~~the etching should be reduced. The Kodak R-10 Bleach~~

~~was modified so that 2 grams potassium iodide per 12~~

~~liters of water were used instead of 128 grams potassium~~

~~iodide per 1 2 liters of water, resulting in better holo~~

~~graphic images and negligible levels of staining as~~

~~compared to the higher concentration of potassium iodide.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 46 Up to this point the process had teen a direct~~

~~bleaching process; the emulsion being developed, fixed,~~

~~and then bleached. By accident, Eariharan, Ramanathan, go and Kaushik ^ treated an unfixed hologram in a dichronate~~

~~bleach containing potassium iodide and obtained a remark~~

~~ably good holographic image. Such a treatment should~~

~~convert the developed silver grains into sites of silver~~

~~iodide and result in a very weak phase image because of~~

~~the small refractive index difference between silver~~

~~bromide (n = 2.25) and silver iodide (n = 2.21). Reasons~~

~~cited for this phenomenon include dissolution of the~~

~~unexposed silver halide grains by the bleach bath as well~~

~~as oxidation of the silver image by the bleach to Ag+~~

~~resulting in the unexposed emulsion grains growing slight~~

~~ly larger forming an intensified phase image. They tried~~

~~different concentrations of potassium iodide in the bleach~~

~~bath and found 2 grams of potassium iodide per 20 liters~~

~~water gave optimum results in diffraction efficiency and~~

~~signal to noise ratio of the holographic image. In the~~

~~same paper it was reported that the bleach of ammonium~~

~~dichromate used in The Kodak R-10 Bleach Process yielded~~

~~poorer overall results than using potassium dichromate~~

~~as the bleaching agent. Although no qualitative data~~

~~were given, they reported that the stability against~~

~~printout was almost as good as silver iodide phase holo~~

~~grams produced by bleaching a silver image by conventional~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4-7~~

~~means and much better than silver bromide phase holograms.~~

~~Further work was done by Eariharan, Kaushik, and~~

~~Hamanathan*^ where they pointed out that the scattered~~

~~optical noise inherent in bleached holograms is proportional~~

~~to the square of the volume of the transparent grains~~

~~representing the image and also learned experimentally~~

~~that the maximum values of diffraction efficiency are~~

~~obtained when only a small fraction of the available silver~~

~~halide in the emulsion is used. Combination of these facts~~

~~means that a controlled etching of the emulsion grains in~~

~~a solution of a suitable silver halide solvent to reduce~~

~~their size will yield a hologram with very low optical~~

~~noise and a very high diffraction efficiency. After~~

~~extensive testing the same group added 0. 5 grams of sodium~~

~~thiosulfate to the developer to act as the etching agent.~~

~~The holographic images were reported to have a significant~~

~~increase in signal to noise ratio (roughly 60 to 1 which~~

~~is comparable to unbleached holograms), without a decrease~~

~~in the diffraction efficiency. To date this is the final~~

~~modification, and this process can be described as a simple~~

~~negative phase image process capable of producing holo~~

~~graphic images of reported high diffraction efficiency and~~

~~low optical noise. The essential processing steps of The~~

~~Modified Developer Process are given in Table 71.~~

~~The Modified Developer Process was by far the simplest~~

~~process of the ones investigated in this paper. The~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 8~~

~~Table 71~~

~~The Essential Processing Steps of The Modified Developer Process~~

~~Step 1 ...... Sodium Thiosulfate~~

~~Step 2 ...... Potassium Dichromate and Potassium Iodide~~

~~brightness and resolution of the holographic image were~~

~~both very good, although no qualitative data were taken.~~

~~The effects of printout darkening were studied in a~~

~~much more qualitative manner. The Modified Developer~~

~~process was further modified in this investigation by the~~

~~omission or substitution of a certain processing step to~~

~~better understand how each step changes the printout~~

~~resistance of the emulsion. The first variation of The~~

~~Modified Developer Process was the replacement of the~~

~~modified developer with D-19. The second variation was~~

~~the replacement of the modified developer with D-76. The~~

~~third variation was the omission of potassium iodide from~~

~~the bleach bath solution. Pigures 14-16 illustrate the transparency response~~

~~of the bleached emulsions to the alterations of The Modified~~

~~Developer Process while Table 711 gives the final absolute~~

~~ana normalized transparencies of these alterations.~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. O Reference, Developed in D-19 A The Modified Developer Process WU bO (MDP) <3 -h -p>-3 o o 60 ^ -p o -P P4 -H

~~-P C 3 efl~~

~~& «H <$ O~~

~~0 1 2 3 4 6 7 8 95 10 Time in Weeks 85~~

~~a> M-P 80 «3;C -P V C-H~~

~~XXX 55 0 4 5 6 8 10 Time in Weeks~~

Figure .14. Time Variation of Absolute and normalized Transparency of Holograms processed with The Modified Developer Process (MDP) and processed with D-19 substituted as the developer in The Modified Developer Process

Figure 15. Time Variation of Absolute and Normalized and Absolute of Variation Time 15. Figure Normalized Percentage Absolute Pe:fcentage of Transmitted Light °f Transmitted Light 65 85 80 r 2 1 0 Transparency of Holograms processed with processed Holograms of Transparency h oiidDvlprPoes (MDP) Process Developer Modified The substituting D-19 and D-76 as developers as D-76 and D-19 substituting 3^5678 9 3^5678 10 A Developed in in Developed A O Reference, Developed in D-19 in Developed Reference, O Time in Weeks in Time Weeks in Time H-76

~~10 50 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light Figure 16. Time Variation of Absolute and Normalized and Absolute of Variation Time 16. Figure 60 0 - 80 40 45 r 0 7 50 65 55 60 0 1 with omission of potassium iodide from iodide potassium of omission with h oiidDvlprPoes (MDP) Process Developer with Modified processed The Holograms of Transparency the bleach bath bleach the substituting D-19 as the developer along developer the as D-19 and developer substituting the as D-19 substituting 2 3 A Developed in D-19 and processed and D-19 in Developed A O Reference, Developed in D-19 in Developed Reference, O Time in Weeks in Time without potassium iodide potassium without Time in Weeks in Time 4 5 6 7 8

~~10 10~~

~~52 Table VII~~

~~Pinal Absolute and Normalized Transparencies of Holograms Processed with The Modified Developer Process and Processed with the Three Modifications Performed on The Modified Developer Process~~

~~Absolute Normalized Transparency Transparency~~

~~Modified Developer Process 54% 72%~~

~~Developed with D-19 41% 63%~~

~~Developed with D-76 43% 70%~~

~~Without Potassium Iodide 44% 6 6 %~~

~~The absolute and normalized transparency of holograms~~

~~processed with The Modified Developer Process were higher~~

~~than those of any of the alterations. Developing with~~

~~D-76 yields holograms which are slightly more transparent~~

~~and more resistive to printout than holograms developed~~

~~with D-19. Printout was less severe when potassium iodide~~

~~was omitted, which is a fact difficult to explain. Per~~

~~haps the small concentration of potassium iodide in the~~

bleach bath does not work as effectively on Agfa emulsions*

~~since The Modified Developer Process was developed to use~~

~~on Kodak 649-P emulsions which are several times thicker.~~

~~Although holograms processed with The Modified Developer~~

~~Process had transparencies and printout resistance supe~~

~~rior to any of the alterations made in this investigation,~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53 the printout "behavior of this process is still quite a~~

~~problem. The quality of the holographic images was slight~~

~~ly superior when processed using The Modified Developer~~

~~Process in comparison to any of the alterations, although~~

~~no qualitative data were taken.~~

~~The Modified Reversal Bleach Process~~

~~The fourth process investigated was The Modified 71 Reversal Bleach Process initiated by Hariharan and 72 finalized by Hariharan and Ramanathan . This process~~

~~can be described as a true reversal bleach system.~~

~~Hariharan and Ramanathan‘ further explored methods~~

~~of converting silver bromide phase holograms to silver~~

~~iodide phase holograms. The problem was to introduce~~

~~the iodide ion in a form which would not result in for~~

~~mation of soluble complexes in the emulsion. Since~~

~~quaternary ammonium iodides behave like strong electro~~

~~lytes when in solution, Ag+ would be readily converted~~

~~to silver iodide and the solubility of silver iodide in~~

~~the solution would be small. They concluded that holo~~

~~grams treated in a 0 .2% solution of tetramethylammonium~~

~~iodide^ resulted in excellent holograms with low optical~~

~~noise, high diffraction efficiency, and good resistance~~

~~to printout. The essential processing steps of The~~

~~Modified Reversal Bleach Process are given in Table VIII.~~

~~The Modified Reversal Bleach Process produced holo-~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54~~

~~Tat>le 7III~~

~~The Essential Processing Steps of The Modified Reversal Bleach Process~~

~~Step 1 ...... Develop in Kodak D-19~~

~~Step 2 ...... Re-expose uniformly to White Light~~

~~Step 3 ...... Redevelop in Kodak D-19~~

~~Step 4 ...... Bleach in Potassium Dichromate~~

~~Step 5 ...... Clear in Tetramethylammonium Iodide~~

~~grams with optical noise lower than any other process~~

~~tested in this paper and diffraction efficiencies as good~~

~~as with any process tested, although no qualitative data~~

~~were taken. The re-exposure to uniform light was found~~

~~to he quite critical as to exposure intensity and time.~~

~~With Agfa 10E70 film the re-exposure was done by a 25~~

~~watt light bulb at a distance of 4 feet for a duration~~

~~of 0 . 5 seconds. The effects of printout were studied in a much more~~

~~qualitative manner. The Modified Reversal Bleach Process~~

~~was further altered in this investigation by the omission~~

~~or substitution of a certain processing step to better~~

~~understand how each step changes the printout resistance~~

~~of the emulsion. The first variation of The Modified~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55 Reversal Bleach Process was the replacement of D- 1 9 with~~

~~3>-76 as the developer. The second variation was the~~

~~substitution of sodium bisulfite for tetramethylammonium~~

~~iodide as the clearer. The third modification was the~~

~~omission of the clearer.~~

~~Figures 17-19 illustrate the transparency response~~

~~of the bleached emulsions to the alterations of The Modi~~

~~fied Reversal Bleach Process while Table IX gives the~~

~~final absolute and normalized transparencies of these~~

~~alterations.~~

~~Table IX~~

Pinal Absolute and Normalized Transparencies of Holograms Processed with The Modified Reversal Bleach Process and Processed with the Three Modifications Performed on The Modified Reversal Bleach Process

~~Absolute Normalized Transparency Transparency~~

~~Modified Reversal Bleach Process 46% 82%~~

~~Developed with D-76 45% 84%~~

~~Cleared with Sodium Bisulfite 49% 74%~~

~~Without Clearer 43% 71%~~

~~The Modified Reversal Bleach Process yields holograms~~

~~which hold 82% of their initial transparencies which clas~~

~~sifies this process as the best yet investigated for~~

permission of the copyrightowner. Further reproduction prohibited without permission Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light Figure 17 • Time Variation of Absolute and Normalized and Absolute of Variation Time 17 •Figure 100 80 - 80 70 40 40 - 60 0 0 1 1 Process and processed with with processed and developer in The Modified Reversal Bleach Reversal Modified The in developer h oiidRvra lahPoes (MRBP) Process Bleach Reversal with Modified processed The Holograms of Transparency 2 2 3 3 A Developed in D-76 in Developed A eeec, (MRBP) Reference, O Time in Weeks in Time Time in Weeks in Time 4 4 7 5 5 D-76 6 6 substituted as the as substituted 7

~~8 8 9 10 9~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light 0 r 70 80 Figure 18. Time Variation of Absolute and Normalized and Absolute of Variation Time 18. Figure clearer in The Modified Reversal Bleach Process Reversal Modified The in clearer and processed with Sodium Bisulfite as the as Bisulfite Sodium (BRBP) with Process processed and Bleach Reversal with Bodified The processed Holograms of Transparency Time in Weeks in Time Time in Weeks in Time eeec, (MRBP) Reference, Processed with Sodium Eisulfite Sodium with Processed as the clearer the as

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

~~Normalized Percentage Absolute Percentage~~

Figure 19* Time Variation of Absolute and Normalized and of Absolute Variation Time 19* Figure of Transmitted Light of Transmitted Light 80 60 40 1 0 The Modified Reversal Bleach Process Bleach Reversal Modified The in clearer the without processed and h oiidRvra lahPoes (MBBP) Process Bleach Reversal Modified The with processed Holograms of Transparency 2 3 A A O O Time in Weeks in Time Time in Weeks in Time Processed without the clearer the without Processed eeec, (MRBP) Reference, 5 6 7 8

~~10 10~~

~~59 resisting printout. Substituting D-76 as the developer~~

~~changed the transparency response very little. Clearing~~

~~with sodium "bisulfite produced holograms which were more~~

~~transparent yet more susceptible to printout than holograms~~

~~cleared in tetramethylammonium iodide. Processed holograms~~

~~which were not cleared were slightly less transparent and~~

~~severely more susceptible to printout than holograms~~

~~cleared either with sodium bisulfite or tetramethyl~~

~~ammonium iodide. Uo significant differences could be seen~~

~~in the holographic images processed by the different~~

~~alterations although no qualitative data were taken.~~

~~The Agfa Process~~

~~The final process investigated was that recommended~~

~~by Agfa-Gevaert*^ to produce phase holograms. The bleach~~

~~utilized is potassium dichromate, the same used by three~~

~~of the processes investigated in this paper.~~

~~The unusual thing about The Agfa Process is that the 76 desensitization bath incorporates phenosafranine as the~~

~~active material. Phenosafranine is a well known red dye~~

~~and was found to be a powerful photographic desensitizer~~

~~by Luppo—Cramer*^ who showed that adding it to a developer~~

~~in one part per twenty thousand enabled the photographic~~

~~plate to be examined in a bright light after only a one~~

~~minute development and also that adding it to a prebath~~

~~enabled development to be carried out in the presence of~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60~~

~~a considerable amount of light, Chang and George*^8~~

~~reported soaking plates in a solution of safranine aconc,~~

~~a material similar in structure to phenosaf ranine, and~~

~~reported that plates turned darker at a slower rate when~~

~~treated with this material. They conjecture that such~~

~~dyes cause the gelatin to absorb strongly in the blue~~

~~acting as a blue filter blocking light off from the silver~~

~~halide grains. The essential processing steps of The~~

~~Agfa Process are given in Table X.~~

~~Table X~~

~~The Essential Processing Steps of The Agfa Process~~

~~Step 1 ...... Develop in Xodak D-19~~

~~Step 2 ...... Bleach in Potassium Dichromate~~

~~Step 3 ...... Clear in Sodium Sulfite and Sodium Hydroxide~~

~~Step 4 ...... Desensitize in Phenosaf ranine~~

~~The Agfa Process produced holograms which yielded~~

~~holographic images which were good as far as brightness~~

~~and resolution are concerned although no qualitative data~~

~~were taken.~~

~~The effects of printout darkening were studied in a~~

~~much more qualitative manner. The Agfa Process was fur~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 61 ther modified in this investigation by the omission or~~

~~substitution of a certain processing step to better~~

~~understand how each step changes the printout resistance~~

~~of the emulsion. The first variation of The Agfa Process~~

~~was the replacement of D-76 for D-19 as the developer.~~

~~The second variation was the omission of phenoseXranine~~

~~from the desensitization bath. The third variation was~~

~~the omission of the entire desensitization bath. The~~

~~fourth variation was the omission of the clearer.~~

~~Figures 20-22 illustrate the transparency response~~

~~of the bleached emulsions to the alterations of The Agfa~~

~~Process while Table XI gives the final absolute and~~

~~normalized transparencies of these alterations.~~

~~Table XI~~

~~Final Absolute and Normalized Transparencies of Holograms Processed with The Agfa Process and Processed with the Four Modifications Performed on The Agfa Process~~

~~Absolute Normalized Transparency Transparency~~

~~Agfa Process 53% 32%~~

~~Developed with D-76 57% 92%~~

~~Without Phenosafranine in the Desensitizer 45% 67%~~

~~Without De sensitizer 46% 70%~~

~~Without Clearer 55% 90%~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 70 ■p O Beference, (AP) *o w © -h A Developed in D-76 ■PhI S3 © •© o © Sh - P 60 © -P P* -H a 0) CQ ■P S3 55 © «J rH St O £-1 CO S> Vi 50 < o

~~0 1 2 3 56 7 8 9 10 Time in Weeks~~

~~100~~

~~fcO-P 05 Si -p V S3-H © 1-3 o Sn © © Pl-P -P ©N 8© 05nr - h a iH © © u 80 O «H » o 10~~

~~Time in Weeks~~

~~Figure 20. Time Variation of Absolute and normalized Transparency of Holograms processed with The Agfa Process (AP) and processed with D-76 substituted as the developer in The Agfa Process~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light Figure 21. Time Variation of Absolute and Normalized and Absolute of Variation Time 21. Figure 100 70 60 80 r 'O 1 0 The Agfa Process (AP) and processed without processed (AP) and Process Agfa The with processed Holograms of Transparency the clearer in The Agfa Process Agfa The in clearer the 2 3 A Processed without the clearer the without Processed A eeec, (AP) Beference, O Time in Weeks in Time Weeks in Time 4- 5 6 7 8 9

~~10 10~~

~~6 4~~

70,- O Reference, (AP) O Processed without the desensitizer -p 65 ©.S3tcbd ca-H A Processed without phenosafranine - P p ! in the desensitizer c 60 © o © Ft -p © -p Ph -H S 55 © © -p S3 3 aJ «—) ^ 50 O =H © C O 45

~~40 ± _L _L 4 5 6 8 10 Time in Weeks~~

~~90 r I~~

~~S3 -H~~

~~10 Time in Weeks~~

Figure 22. Time Variation of Absolute and normalized Transparency of Holograms processed with The Agfa Process (AP;, processed without phenosafranine in the desensitizer of The Agfa Process, and processed without the desensitizer in The Agfa Process

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65~~

~~Holograms developed in D-76 had suprisingly higher~~

~~transparencies and higher resistance to printout than~~

~~holograms developed in D-19. Holograms processed without~~

~~phenosafranine in the desensitization hath exhibited the~~

~~lowest transparency levels and lowest resistance to print~~

~~out of any alteration indicating that phenosafranine is~~

~~a very powerful substance in producing holograms which~~

~~have high transparency and high resistance to printout.~~

~~Holograms processed without the desensitization bath have~~

~~transparency responses quite similar to holograms proc~~

~~essed without just phenosafranine. These curves therefore~~

~~justify the statement that phenosafranine is the only~~

~~active chemical in the desensitization bath optimizing~~

~~holographic transparency responses. Holograms processed~~

~~without the clearer were more transparent and less sus~~

~~ceptible to printout than holograms processed with The~~

~~Agfa Process, indicating that the chemicals sodium hy~~

~~droxide and sodium sulfite in the clearer do little~~

~~clearing, but do sensitize the emulsion slightly to~~

~~printout darkening. No significant differences could be~~

~~seen in the holographic images processed by the different~~

~~alterations, although no qualitative data were taken.~~

~~Removal of the clearing bath, developing in D-76, and~~

~~using phenosafranine as a desensitizer yields holograms~~

~~which hold about 9 0% of their initial transparency, by~~

~~far the best process investigated for resisting printout.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER YI~~

~~ATTEMPTS TO IMPROVE HOLOGRAPHIC IMAGES~~

~~In addition to testing the five processes described~~

~~previously, other attempts were made to develop bleached~~

~~holographic images of better quality as well as trying~~

~~to understand more fully the printout phenomenon.~~

~~Printout Resulting from Variable Light Intensities~~

~~The first experiment designed was to try to correlate~~

~~the printout effect as a function of light intensity~~

~~incident upon the processed hologram. Five holograms~~

~~were processed using The Modified Developer Process and~~

~~five processed using The Modified Reversal Eleach Process.~~

~~A hologram from each process was placed at distances of~~

~~8, 4, 2, 1, and 0.5 feet from a 75 watt incandescent~~

~~light bulb. The holograms were illuminated twenty-four~~

~~hours a day and monitored on the Bausch and Lomb micro-~~

~~photometer every three days in the same manner as de~~

~~scribed previously. Pigures 23 and 2-‘: show the trans~~

~~parency and printout behavior of each hologram as a~~

~~function of time.~~

~~Por The Modified Developer Process the final trans~~

~~parency levels are as follows; 8 feet, 82%; 4 feet, 80%;~~

~~2 feet, 76%; 1 foot, 64%; 0.5 feet, 63%. The same values~~

~~for The Modified Reversal Bleach Process are as follows:~~

~~8 feet, 89%; 4 feet, 85%; 2 feet, 79%; 1 foot, 65%; 0.5 66~~

Figure 23* Time Variation of Absolute and normalized and Absolute of Variation Time 23* Figure Absolute Percentage of Transmitted Light 35 50 55 65 60 inducing light source light printout inducing a from distances various at The Modified Developer Process arranged Process Developer Modified The Transparency of Holograms processed with processed Holograms of Transparency Time in Days in Time 2 5 8 21 18 15 12 . foot 0.5 4 feet 4 1 foot 1 8 feet 8 2 feet 2

~~67 60 70 80 omlzd ecnae f rnmte Light Transmitted of Percentage Normalized V~~

~~8 f e e t 6 8 4 feet 6 5 r 2 feet 100~~

~~■p 95 § s i I •© 90 £ Q> © -P P* -P *ri ►d e © CD c 85 g cS Ft © e* c f ©~~

~~12 15 18 Time in Days~~

~~Figure 24. Time Variation of Absolute and normalized Transparency of Holograms processed with The Modified Reversal Bleach Process arranged at various distances from a printout inducing light source~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 69~~

~~feet, 70%. Although the relationship is not simple, it~~

~~does appear that the printout effect is more severe as~~

~~the light intensity increases.~~

~~Printout Resulting from Wavelength Variation of Light~~

~~The second experiment was designed to study the~~

~~printout effect as a function of the wavelength of light~~

~~striking the emulsion. Six holograms were processed using~~

~~The Modified Reversal Bleach Process and each was placed~~

~~behind a filter which allowed only monochromatic light~~

~~to strike it. The light source was an incandescent light~~

~~bulb and the filters were arranged so that equal inten~~

~~sities of monochromatic light struck each hologram. The~~

~~transparency of each hologram was monitored by the Bausch~~

~~and Lonb microphotometer as described previously. Figure~~

~~25 shows the transparency and printout behavior of each~~

~~hologram as a function of time.~~

~~After a thirty day period of time the following~~

~~transparency percentages of the original transparency~~

~~were recorded: yellow filter, 73%; green filter, 79%;~~

~~blue filter, 80%; blue-green filter, 84%; opaque filter~~

~~(no light striking the emulsion), 92%; red filter, 95%.~~

~~Although the results are inconclusive as far as~~

~~finding a working correlation between wavelength and~~

~~printout darkening, they do show a couple of notable~~

~~features: 1) holograms tend to darken even in the dark,~~

Figure 25* Time Variation of Absolute and Normalized and Absolute of Variation Time 25* Figure Absolute Percentage of Transmitted Light 60 0 3 in front of a printout inducing light inducing printout a of placed front filters in different with Process Bleach arranged Reversal Hodified The Transparency of Holograms processed with processed Holograms of Transparency 6 1 1 1 2 2 2 30 27 24 21 18 15 12 9 Time in Bays in Time Black □ Blue-Green Blue Yellow Green

~~100~~

~~80 omlzd ecnae f rnmte Light Transmitted of Percentage Normalized 71 2) putting holograms in an environment where only red~~

~~filters are used for illumination will insure a long life~~

~~for holograms with respect to printout darkening.~~

~~Printout Hesuiting from Ultrasonic Agitation~~

~~In attempting to develop bleached holographic images~~

~~of better resolution and brightness, the idea of trying~~

~~to produce finer grained emulsions was explored. The~~

~~reason for producing an emulsion with smaller grain size~~

~~would be an increased probability in higher resolution~~

~~of the holographic image.~~

~~In a typical ultrasonic cleaner a drop of mercury~~

~~after a short period of time will be completely disso~~

~~ciated throughout the containing bath of water. If an~~

~~unexposed photographic emulsion was placed in an ultra~~

~~sonic cleaner, it might be reasonable to expect that the~~

~~emulsion grains would be broken down into smaller par~~

~~ticles. Unexposed Agfa 10E70 film was processed in a~~

~~Bendix Sonic Energy Cleaner*^ for a five minute period~~

~~of time. The film was then allowed to air dry for three~~

~~days. Holograms were then processed in one of three ways:~~

~~1) developed in D-19, then bleached in potassium di-~~

~~chromate; 2) developed in D-19, bleached in potassium~~

~~dichromate, then desensitized in phenosafranine; 5)~~

~~developed in D-19» re—exposed to uniform light, re~~

~~developed in D-19 (reversal bleached), then desensitized~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 72~~

~~in phenosafranine. Figure 26 shows the transparency and~~

~~printout behavior of each modification as a function of~~

~~time.~~

~~Holograms processed by methods two and three produced~~

~~very weak holographic images while the images produced~~

~~in method number one were only fair. The transparency~~

~~of holograms processed v/ith the ultrasonic unit went from~~

~~42% to 52%. Holograms processed by method number one held~~

~~only 63% of their initial transparency after a thirty day~~

~~period of time while method number two holograms eventu~~

~~ally held 98% of the initial transparency after recovery~~

~~from 83% after three days and method number three holo~~

~~grams eventually held 94% of the initial transparency~~

~~after recovery from 81% after a three day period. Al~~

~~though holograms processed using the ultrasonic unit have~~

~~images which range from fair to poor, their printout~~

~~resistance is very high when suitably processed.~~

~~Ultrasonic Agitation Effect upon Wavelength Sensitivity~~

~~The Bendix Sonic Energy Cleaner was also used in 80 studying the effects of processing Kodak S.A.-3 spectro-~~

~~graphic plates through the cleaner with regard to possible~~

~~increased resolution of spectral lines. An S.A.-3 plate~~

~~was placed in the ultrasonic cleaner for five minutes,~~

~~let dry for five days, and then positioned in a Hilger~~

~~Medium Quartz Spectrograph®^. A rotating step sector was~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. to r 73. O Developed and bleached 4* 9Sl 65 - O Developed, bleached, and desensitized 00 M 05 *H +» p! A Developed, reversal bleached, C 9 * 0 60 “ and desensitized O

~~40 12 15 18 21 24 27 30 Time in Days 100~~

~~65 X ± 12 15 18 h Si 2*7-- 3^ Time in Days~~

~~Figure 26* Time Variation of Absolute and Normalized Transparency of Holograms processed with different modifications after agitation of the unexposed film in an ultrasonic cleaner~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 74 positioned in front of the spectroscopic slit and twin~~

~~iron electrodes were "burned "by an arc source for a forty~~

~~second duration. She plate was then developed in D-19~~

~~for five minutes, put in a stop "bath for fifteen seconds,~~

~~and finally fixed for three minutes in Kodak Eapid Fixer.~~

~~Another S.A.-3 plate was processed in the exact same~~

~~manner except that this plate was not agitated in the~~

~~ultrasonic cleaner. After comparison of the dried plates~~

~~no resolution difference could "be seen in spectral lines;~~

~~however, the ultrasonically agitated plate appeared to~~

~~have slightly darker spectral lines. An H & D curve was~~

~~plotted from the unagitated plate and the darknesses of~~

~~spectral lines were compared at intervals of about 250~~

~~angstroms.~~

~~The ultrasonically agitated plate had spectral lines~~

~~consistently darker than those on the unagitated plate,~~

~~running from equal intensities to 1.4 times as dark. The~~

~~significant point about the study is the fact that in the~~

~~region of 4750 angstroms to 5300 angstroms the spectral~~

~~lines were 1.3 to 1.4 times darker on the ultrasonically~~

~~agitated plate, a fact hard to explain away by processing~~

~~chemical changes, slight differences in spectroscopic~~

~~processing, or initial differences between the plates.~~

~~Figure 27 shows the ratio of spectral line darknesses~~

~~as a function of wavelength.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 75~~

Pigure 27. Wavelength. Variation of the Darknesses of Spectral Lines on a Kodak S.A.-3 Spectro- graphic Plate Agitated in an Ultrasonic Cleaner before Exposure divided by the Darknesses of Spectral Lines on an Unagit&ted S.A.-3 Plate

~~Effect of Toners on Brightness and Resolution~~

~~A study of toners was also made in the hope that out~~

~~of this branch of photographic processing a method could~~

~~be found to produce holographic images of superior quality.~~

~~Normally processed amplitude holograms were toned in~~

~~one of four toner solutions: 1) Hypo Alum Toner (Agfa 222),~~

~~2) Iron Blue Toner (Agfa 241), 3) Sulfide Toner (Kodak T-~~

~~10), 4) Uranium Toner (Kodak T-9). Although no quali~~

~~tative data were taken, the holographic image brightness~~

~~and resolution were not improved with any of the toners~~

~~but actually decreased in cases. A conclusion must be~~

~~reached that toning of a hologram produces no improvement~~

~~of the holographic image.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Liquid Gates and Holographic Resolution~~

~~Several articles in the literature(82“88) have~~

~~mentioned using liquid gates to try to improve the reso~~

~~lution of holographic images. Ideally this liquid gate~~

~~would match the index of refraction of the gelatin and~~

~~fill in any scattering centers produced by the formation~~

~~of a relief image on the emulsion surface or by pock marks~~

~~in the emulsion where metallic silver sites have been~~

~~vacated by bleaching.~~

~~Seven materials were investigated as to their ability~~

~~to increase holographic image resolution when used as~~

~~liquid gates on holograms produced on Agfa 10E70 films.~~

~~The materials are as follows: 1) Xylene8^, 2) methyl~~

~~Benzoate^8, 3) Chlorobenzene^, 4) Bromoethane^, 5)~~

~~p-Chlorotoulene^, 6) 1,2-Dibromopropane^., 7) 1,3-~~

~~Dibromopropane^. All of these materials have refractive~~

~~index of approximately 1.50, the same as photographic~~

~~gelatin.~~

~~The liquid gates were formed by gluing with rubber~~

~~cement a round washer made of bone onto the emulsion~~

~~surface, filling the washer with the material, then~~

~~cementing a thin glass slide onto the top of the washer.~~

~~Although no qualitative data were taken, holographic~~

~~image resolution did not change with any of the materials~~

~~tested except xylene, where the image resolution was~~

~~severely decreased. The probable formation of very small~~

~~. \ .1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 77~~

~~relief images on the relatively thin Agfa 10E70 emulsion~~

~~might he one possibility as to why there is no resolution~~

~~improvement.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER VII~~

~~SELECTING AH OPTIMUM HOLOGRAPHIC PROCESS~~

~~After the investigations were performed on the five~~

~~processes described previously in Chapter IV, it was noted~~

~~that combining the good aspects of some processes could~~

~~possibly result in a general all around better process~~

~~for producing phase holograms. Holograms were processed~~

~~in one of the following twelve ways: 1) developed, then~~

~~bleached; 2) developed, bleached, then processed in tetra-~~

~~methylammonium iodide; 3) developed, bleached, processed~~

~~in tetramethylammonium iodide, then processed in pheno~~

~~safranine; 4) prehardened, developed, bleached, processed~~

~~in tetramethylammonium iodide, then processed in pheno~~

~~safranine; 5) developed, then reversal bleached; 6) de~~

~~veloped, reversal bleached, then processed in phenosaf~~

~~ranine; 7) developed, reversal bleached, then processed~~

~~in tetramethylammonium iodide; 8) developed, reversal~~

~~bleached, processed in tetramethylammonium iodide, then~~

~~processed in phenosafranine; 9) developed in D-19, then~~

~~bleached with The Modified Stanford Process bleach; 10)~~

~~developed in D-19, fixed, then bleached with The Modified~~

~~Stanford Process bleach; 11) developed in D-19, bleached~~

~~with The Modified Stanford Process bleach, then processed~~

~~in phenosafranine; 12) developed in D-19, fixed, bleached~~

~~with The Modified Stanford Process bleach, then processed 78~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 79~~

~~in phenosafranine. Unless otherwise indicated, the de- -~~

~~veloper used was the modified developer investigated in~~

~~The Modified Developer Process and unless otherwise indi~~

~~cated the bleaching agent was potassium dichromate. These~~

~~twelve modifications are summarized in Table XII.~~

~~Figures 28-33 illustrate the transparency response~~

~~of the bleached emulsions to the alterations described~~

~~previously while Table XIII gives the final absolute and~~

~~normalized transparencies of these alterations.~~

~~Holograms processed by methods number one and two~~

~~both yielded final transparency levels of 4-2%, which was~~

~~75% of the initial transparency for method number one as~~

~~compared to 79% of the initial transparency for method~~

~~number two holograms. This indicates that processing in~~

~~tetramethylammonium iodide does help in resisting printout~~

~~by about 4% without changing the opacity of the hologram.~~

~~The final transparency of method number three holograms~~

~~was 44%, which was 90% of the original transparency. This~~

~~shows that phenosafranine increased the normalized trans~~

~~parency by 11% over holograms processed without it, even~~

~~increasing the final transparency in doing so. The final~~

~~transparency of method number four holograms was 47%, which~~

~~was 87% of the initial transparency. It seems that pre~~

~~hardening increases the transparency somewhat but also~~

~~lowers the printout resistance slightly. The final trans~~

~~parency of method number five holograms was 46%, which was~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8 0 Table H I~~

~~Summary o f The Western Michigan University Modifications~~

~~MODIFICATION DESCRIPTION~~

~~1 ...... Developed, then bleached~~

~~2 ...... Developed, bleached, then cleared~~

~~3 ...... Developed, bleached, cleared, then desensitized~~

~~4- ...... Prehardened, developed, bleached, cleared, then desensitized~~

~~5 ...... Developed, then reversal bleached~~

~~6 ...... Developed, reversal bleached, then desensitized~~

~~7 ...... Developed, reversal bleached, then cleared~~

~~8 ...... Developed, reversal bleached, cleared, then desensitized~~

~~9 ...... Developed with D-19, then bleached with CuBr2 + PeCl^~~

~~1 0 ...... Developed with D-19, fixed, then bleached with CuBr2 +■■■ PeCl^~~

~~1 1 ...... Developed with D-19, bleached with CuBr2 + PeCl^, then desensitized~~

~~1 2 ...... Developed with D-19* fixed, bleached with CuBr2 + PeCl^, then desensitized~~

Unless otherwise indicated the developer used was The Mod ified Developer investigated in chapter 17, and the bleach ing agent was potassium dichromate. The clearer refers to tetramethylammonium iodide and the desensitizer refers to phenosafranine.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60~~

~~p ox! 55 O WMU Modification Number 1 «0 <30 9) P P P A WMU Modification Number 2 c © T J 50 O © -P © - P P* Pc 45 © © - P f j 3~~

~~30 XXX 12 15 18 21 24 27 30 Time in Days~~

~~60 X XX 12 15 18 21 24 27 30 Time in Days~~

~~Figure 28. Time 'Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications One and Two~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light Figure 29. Time Variation of Absolute and Normalized and Absolute of Variation Time 29. Figure 40 80 0 3 Western Michigan University Modifications University Michigan Western Two and Three and Two processed, Holograms of with Transparency 6 A A O O 1 1 1 2 2 2 30 27 24 21 18 15 12 9 WMU Modification Number 2 Number Modification WMU WMU Modification Number Number Modification WMU Time in Days in Time Days in Time 2 5 18 15 12

~~21 3~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light lOOp Figure 30. Time Variation of Absolute and Normalized and Absolute of Variation Time 30. Figure 80 J 3 9 2 5 8 1 4 7 30 27 24 21 18 15 12 9 6 3 0 ---- 1 --- Western Michigan University Modifications University Michigan Western Three and Four and Three Transparency of Holograms processed with processed Holograms of Transparency 1 ---- A O 1 ---- Time in Lays in Time Time in Lays in Time WMU Modification Number 4 Number Modification WMU 3 Number Modification WMU 1 __ I ____ I ____ I____I ___ I 1

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

~~Normalized Percentage Absolute Percentage~~

Figure 31. Time Variation of Absolute and Normalized and Absolute of Variation Time 31. Figure of Transmitted Light of Transmitted Light 100 70 65 50 60 55 0 0 3 3 Five, Six, and Seven and Six, Five, Modifications University Michigan Western Transparency of Holograms processed with processed Holograms of Transparency 6 6 1 1 1 2 2 2 30 27 24 21 18 15 12 9 Q O O A O O Time in Lays in Time WMU Modification Number Modification WMU WMU Modification Number Modification WMU WMU Modification Number Modification WMU 2 5 8 1 4 7 30 27 24 21 18 15 12 Time in Lays in Time

~~84 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

Normalized Percentage Absolute Percentage of Transmitted Light of Transmitted Light 100 110 105 0rA r 70 Figure 32. Time Variation of Absolute and Normalized and of Absolute Variation Time 32. Figure - Western Michigan University Modifications University Michigan Western Six, Seven, and Bight and Seven, Six, Transparency of Holograms processed with processed Holograms of Transparency O WMU Modification Number 6 Number Modification WMU O WMU Modification Humber 7 Humber Modification WMU WMU Modification Number 8 Number Modification WMU Time in Days in Time 2 5 8 1 24 21 18 15 12 ie n Days in Time 12 18 24

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced~~

Normalized Feroentage Absolute Percentage of Transmitted Light of Transmitted Light 110 100 120 45 40 80 Figure 33. Time Variation of Absolute and Normalized and Absolute of Variation Time 33. Figure 70 „ 70 35 60 65 50 55

0 3 Nine, Ten, Eleven, and Twelve and Eleven, Ten, Nine, Western Michigan University Modifications University Michigan Western Transparency of Holograms processed with processed Holograms of Transparency 6 1 1 1 2 2 2 30 27 24 21 18 15 12 9 A O O Q HOT 0 Time in Lays in Time Lays in Time HOT HOT WMU 11 Number Modification oiiainnme 9 number Modification Modification Number 10 Number Modification Modification Number Number 12 Modification 4 7 30 27 24 ^ — - A

~~Table XIII~~

~~Pinal Absolute and Normalized Transparencies of Holograms Processed with The Twelve Western Michigan University Modifications~~

~~Absolute Normalized Transparency Transparency~~

~~Modification Number 1 42% 75%'~~

~~Modification Number 2 42% 79%~~

~~Modification Number 3 44% 90%~~

~~Modification Number 4 47% 87%~~

~~Modification Number 5 46% 71%~~

~~Modification Number 6 63% 90%~~

~~Modification Number 7 63% 101%~~

~~Modification Number 8 62% 105%~~

~~Modification Number 9 52% 91% Modification Number 10 66% 96%~~

~~Modification Number 11 53% 114%~~

~~Modification Number 12 69% 107%~~

~~only 71% of the initial transparency. The final trans~~

~~parency of method number six holograms was 63%» which was~~

~~90% of the initial transparency, indicating that pheno~~

~~safranine increased transparency by 17% and printout~~

~~resistance by 19%. The final transparency of method number~~

~~seven holograms was 63%» which was 101% of the initial~~

~~transparency • The transparency level dropped to 96% of~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. r-~~

~~88 the original after three days but quickly recovered to~~

~~the final value. Tetramethylammonium iodide thus in~~

~~creased the transparency by 16% and the resistance to~~

~~printout by 30%. The final transparency of method number~~

~~eight holograms was 62% which was 105% of the initial~~

~~transparency, this level never dropping to less than~~

~~100% and never going above 106%. It appears that with~~

~~reversal bleached holograms tetramethylammonium iodide~~

~~has a greater resistance to printout than does pheno-~~

~~safranine, just the opposite of what occurs with holograms~~

~~processed with a negative phase image process. The final~~

~~transparency of method number nine holograms was 52%,~~

~~which was 91% of the original transparency. However,~~

~~this normalized value was only 66% after three days, re~~

~~covering slowly as time progressed. The final transparency~~

~~of method number ten holograms was 66%, which was 96% of~~

~~the original transparency. This normalized value dropped~~

~~to 89% after three days but slowly recovered to the present~~

~~value. Since this recovery phenomenon occurs both with~~

~~fixed and unfixed holograms, the recovery must be linked~~

~~with the bleach bath used in The Modified Stanford Process.~~

~~The final transparency of method number eleven holograms~~

~~was 53%» which was 114% of the initial value, the lowest~~

~~normalized value being 99% after three days. The final~~

~~transparency of method number twelve holograms was 69%,~~

~~which was 107% of the initial value, the lowest normalized~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 89~~

~~value "being 99% after six days. It appears that pheno-~~

~~safranine staves off the initial severe degradation~~

~~inherent to holograms "bleached with The Modified Stanford~~

~~Process "bleach and then they recover above "the initial~~

~~transparency "by some mechanism still unclear, "but very~~

~~possibly connected to the materials used in the bleach~~

~~bath.~~

~~Holograms processed with methods number eight and~~

~~twelve were the only ones which showed excellent resis~~

~~tance to printout, high transparency, and good emulsion~~

~~stability. Therefore, further trials were done on holo~~

~~grams bleached in one of three manners: 1) developed~~

~~in The Modified Developer Process developer, reversal~~

~~bleached in potassium dichromate, cleared in tetramethyl~~

~~ammonium iodide, then desensitized in phenosafranine;~~

~~2) developed in D-19» fixed, bleached in ferric chloride~~

~~and cupric bromide, then cleared in tetramethylammonium~~

~~iodide; 3) developed in 3)-19» fixed, bleached in ferric~~

~~chloride and cupric bromide, then desensitized in pheno~~

~~safranine. Figure 34 shows the transparency and printout~~

~~behavior of each modification as a function of time. The~~

~~above modifications are identified in Figure 34 as 4A,~~

~~12A, and 12B respectively.~~

~~The final transparency of modification 4A holograms~~

~~was 66%, which was 103% of the initial transparency.~~

~~Never did this normalized value go below 100% or above~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65 •p ©.S3 t>0 taO Cfl t 1 60 - P F 3 C © o ® WMU Modification Number 4A h +> 55 © -p PM -H WMU Modification Number 12A S © © 50 WMU Modification Number 12B s § ri Pi O E -t Q /3«tH 45 <5 O

~~12 15 18 Time in Bays~~

~~125 r~~

~~95 ± JL _L 12 15 18 21 24 27 50 Time in Bays~~

~~Figure 34. Time Variation of Absolute and Normalized Transparency of Holograms processed with Western Michigan University Modifications 4A, 12A, and 12B~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 91 104%. Shis indicates that processing with this modifi~~

~~cation produces holograms which have very stable compounds~~

~~residing in the emulsion. The final transparency of~~

~~modifications 12A and 12B was 47% and 61% respectively~~

~~which was 123% and 117% of their initial transparency.~~

~~This recovery is representative of holograms bleached in~~

~~cupric bromide and ferric chloride. One may question if~~

~~this drastic recovery of holographic transparency degrades~~

~~the image; however, no significant change could be observed~~

~~visually in the holographic images which were processed~~

~~in this fashion.~~

~~Western Michigan University Modifications Humber~~

~~12A and 12B will be described as The Derby Process and~~

~~western Michigan university Modification Humber 4A will~~

~~be described as The Markham Process in Tables XIV and XY~~

~~and appendices VI and VII respectively.~~

~~Table XIV~~

~~The Essential Processing Steps of The Derby Process~~

~~Step 1 ...... Develop in Kodak D-19~~

~~Step 2 ...... Fix in Kodak Sapid Fixer~~

~~Step 3 ...... Bleach in Cupric Bromide and Ferric Chloride~~

~~Step 4 ...... Desensitize in Phenosafranine and/or Clear in Tetramethylammonium Iodide~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table XV~~

~~The Essential Processing Steps of The Markham Process~~

~~Step 1 ...... Develop in Kodak D-19 and Sodium Thiosulfate~~

~~Step2...... Ee-expose uniformly to white light~~

~~Step 3 . . . ..Eedevelop in Kodak D-19 and Sodium Thiosulfate~~

~~Step 4- ...... Clear in Tetramethylammonium Iodide~~

~~Step 5 ...... Desensitize in Phenosafranine~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CONCLUSIONS~~

~~A process has been developed which produces photo~~

~~graphic phase holograms of high diffraction efficiency,~~

~~low noise, and high resistance to printout darkening.~~

~~The process was developed by combining the best qualities~~

~~of some of the latest processes reported in the literature.~~

~~The first innovation was the use of a modified developer~~

~~which consists of a very small amount of sodium thic-~~

~~sulfate added to Kodak D-19. This developer slightly~~

~~etches the undeveloped silver bromide particles in the~~

~~emulsion making then smaller and as a result they scatter~~

~~less light giving increased resolution to the holographic~~

~~image. The second innovation utilizes the concept of~~

~~reversal bleaching. After the initial development the~~

~~entire hologram is then re-exposed to uniform white light~~

~~and after a second development and bleaching of the emul~~

~~sion only the grains of silver bromide shielded by the~~

~~metallic silver produced by the first development remain~~

~~in the emulsion. These remaining grains, called the~~

~~reversed image, contain all of the information which was~~

~~recorded on the emulsion prior to the first development.~~

~~Due to this reversal bleaching process, the scattering~~

~~of the emulsion has been cut significantly because most~~

~~of the original silver bromide particles have been proc~~

~~essed away. The third innovation was the use of tetra-~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 94~~

~~methylammonium iodide to convert the silver bromide par~~

~~ticles remaining in the emulsion into silver iodide.~~

~~Silver iodide resists printout darkening much more than~~

~~does silver bromide, and tetramethylammonium iodide being~~

~~a strong electrolyte in solution converts very satis~~

~~factorily the grains into silver iodide without the~~

~~etching of these grains which does occur with other~~

~~processes. The fourth innovation was the use of pheno-~~

~~safranine to desensitize the emulsion from printout~~

~~darkening. Phenosafranine is a red dye which is thought~~

~~to cause the gelatin to absorb short wavelength light.~~

~~This absorption thus removes the high energy photons~~

~~which apparently are more active in causing printout.~~

~~A direct bleach process using cupric bromide and~~

~~ferric chloride as the bleaching agent, followed by~~

~~processing in tetramethylammonium iodide and/or pheno~~

~~safranine, produces holograms which resist printout~~

~~darkening but have slightly less resolution of the images~~

~~than the process described previously. The advantage of~~

~~this process is that it is very simple and only one of~~

~~two exotic chemicals need be obtained. The process~~

~~described previously involves many steps including a~~

~~re—exposure which is somewhat difficult to control.~~

~~Other methods of trying to improve photographic phase~~

~~holograms did not produce as good results. Holograms~~

~~were toned in the hopes that higher diffraction efficien—~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 95~~

~~cies could be observed. Holograms were immersed in index~~

~~of refraction matching liquids in the hopes that lower~~

~~. optical noise levels could be produced. Holographic film~~

~~was agitated in an ultrasonic cleaner in the hopes of~~

~~creating smaller grain sizes in the emulsion and gaining~~

~~resolution of the holographic images. In all cases the~~

~~results turned out disappointing.~~

~~After twenty seven days of constant exposure by an~~

~~incandescent lamp, holograms situated at different dis~~

~~tances from the lamp recovered significantly in trans~~

~~parency after the lamp was found to have burned out~~

~~between twenty seven and thirty days of constant exposure.~~

~~This indicated that after exposure to light, holograms~~

~~recover some of their initial transparency if they are~~

~~placed in darkness. A further study is suggested to~~

~~determine the effects of pulsed light of different fre~~

~~quencies on the printout stability of bleached holograms.~~

~~Although using the ultrasonic cleaner for improving~~

~~holographic image quality failed, a Kodak S.A.-3 plate~~

~~agitated in the device produced slightly darker spectral~~

~~lines than a plate not agitated. The lines were almost~~

~~1.5 times as dark on the red end of the spectrum. A fur~~

~~ther study is suggested to determine if agitating certain~~

~~emulsions in an ultrasonic cleaner produces increased~~

~~sensitivity at certain wavelengths.~~

~~In the bleached holograms of this investigation, the~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. phenomena of printout and subsequent partial recovery are~~

~~thought to he related to the solarization processes in~~

~~ordinary photography. The response of the bleached holo~~

~~grams to prolonged illumination is characterized by the~~

~~various experimental curves shown in this paper. These~~

~~curves all have similar shapes and most display a region~~

~~of decreasing transparency followed by a region of in~~

~~creasing transparency, although the different curves show~~

~~these effects in varying degrees. This transparency~~

~~decline and partial recovery is represented by the typical~~

~~curve of figure 35.~~

~~Percent a Transparency |~~

~~Time — ^~~

~~Figure 35. Time Variation versus Absolute Transparency for a Typical Bleached Hologram~~

~~The printout region AB illustrates a period of time~~

~~during which the sustained illumination on the hologram~~

~~is causing an emulsion darkening. The increased density~~

~~of the emulsion is thought to be caused by the photolytic~~

~~generation of atomic metallic silver both within the silver~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 97 halide crystals and on their surfaces. The progressive~~

~~darkening continues until it "bottoms out (at B) due to~~

~~a competing re-brominization process.~~

~~The transparency recovery region BC may be explained~~

~~by the gradual decrease in the ratio of the printout~~

~~silver on the halide grain surface compared to printout~~

~~silver in the grain interior. The halogen is usually~~

~~liberated at the grain surface where it can unite with~~

~~the surface silver, while the grain itself (via hole~~

~~transport mechanism) tends to protect the internal print~~

~~out silver. The decrease of printout silver from the~~

~~grain surface and the increase of interior printout silver~~

~~results in an overall effect of increased transparency~~

~~of the hologram. The decrease in absorption is related~~

~~to an effective decrease in the absorbing area of the~~

~~printout silver.~~

~~The research of this paper has generated two sig~~

~~nificant modifications on photographic phase hologram~~

~~processing. These have been identified in Tables XIV~~

~~and XV and described in detail in appendices VI and VII~~

~~as The Derby Process and The Markham Process respectively.~~

~~These processes are particularly valuable in producing~~

~~photographic phase holograms with high transparency~~

~~levels which experience less printout than by any other~~

~~known method.~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX I~~

~~PROCESSING STEPS FOR THE MODIFIED STANFORD PROCESS~~

3 Min. 1) Preharden in Kodak Prehardener SH-5 5 Min. 2) Develop in Kodak D-19 15 Sec. 3) Stop Bath 3 Min. 4) Fix in Kodak Rapid Fixer 10 Min. 5) Rinse in Distilled Water 7 Min. 6) Bleach 30 Sec. 7) Rinse in Distilled Water 1 Min. 8) Clear and Desensitize 10 Min. 9) Rinse in Distilled Water 5 Min. 10) Dry in 50% Methanol 3 Min. 11) Dry in 100% Methanol 12) Dry Slowly at Room Temperature

~~BLEACH Ferrous Chloride 25 grams Cuprous Bromide ...... • • 25 grams Concentrated Sulfuric Acid « . • 15 milliliters Distilled Water ...... 500 milliliters~~

C L E A R and DESENSITIZE Solution A Potassium Permanganate • . . • • 5 grams Distilled Water ...... 1 liter Solution B Potassium Bromide • ••...• 50 grams Concentrated Sulfuric Acid • . • 10 milliliters Distilled Water ...... 1 liter ( 1 part of A to 10 parts of B )

~~permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX II~~

~~PROCESSING STEPS FOR THE KODAK REVERSAL BLEACH SYSTEM~~

5 Min. 1) Develop in Kodak Special Developer SD-48 15 Sec. 2) Stop Bath 1 Min. 3) Rinse in Running Water 3 Min. 4) Bleach 5 Min. 5) Rinse in Running Water 1 Min. 6) Stain Remover 1 Min. 7) Clearer 8 Min. 8) Rinse in Running Water 5 Min. 9) Dry in 50% Methanol 10) Wash Twice in Isopropyl Alcohol

KODAK SPECIAL DEVELOPER SD-48 Solution A Sodium Sulfite ...... 8 grams Pyrocatechol...... 40 grams Sodium Sulfate 100 grams Distilled Water ...... 1 liter Solution B Sodium H ydro x i d e...... 20 grams Sodium Sulfate ...... 100 grams Distilled Water 1 liter ( 1 part of A to 1 part of B just before using )

~~BLEACH Potassium Bichromate ...... 9.5 grams Concentrated Sulfuric Acid . . . 12 milliliters Distilled Water ...... 1 liter~~

~~STAIN REMOVER Potassium Permanganate • • • • • 2.5 grams Concentrated Sulfuric Acid . . . 8 milliliters Distilled Water ...... 1 liter~~

~~CLEARER Sodium Bisulfite ...... 10 grams Distilled Water ...... 1 liter 99~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX III~~

~~PEOCESSING STEPS POE THE MODIPIED DEVELOPEE PEOCESS~~

~~5 Min. 1) Develop in The Modified Developer 3 Min. 2) Einse in Distilled Water 5 Min. 3) Bleach 6 In. 4) Einse in Distilled Water~~

~~THE MODI PIED DEVELOPEE Kodak D - 1 9 ...... 1 liter Sodium Thiosulphate 0.5 gram~~

BLEACH Solution A Potassium Dichromate...... 8 grams Concentrated Sulfuric Acid . . . 10 milliliters Distilled W a t e r ...... 1 liter Solution B Potassium Iodide ...... 2 grams Distilled W a t e r ...... 1 liter ( 1 part of A to 1 part of B to 8 parts of distilled water just Before using )

~~100~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX IT~~

~~PROCESSING STEPS POR THE MODI PIED REVERSAL “BLEACH PROCESS~~

5 Min. 1) Develop in Kodak D-19 90 Sec. 2) Rinse in Distilled Water 3) Re-expose Uniformly to White Light (Approximately 15 sec. to a 15-W bulb at 1 meter for Kodak 649-P plates and approximately .5 sec. to a 25-W bulb at 4 feet for Agfa-Gevaert 103570 film) 5 Min. 4) Redevelop in Kodak D-19 3 Min. 5) Rinse in Distilled Water 12 Min. 6) Bleach 3 Min. 7) Rinse in Distilled Water 5 Min. 8) Clear 9 Min. 9) Rinse in Distilled Water

~~BLEACH Potassium Dichromate...... 0.4 gram Concentrated Sulfuric Acid . . .0.5 milliliter Distilled W a t e r ...... 1 liter~~

~~CT.TgATTER Tetramethylammonium Iodide . . . 2 grams Distilled Water . • ...... 1 liter~~

~~101~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX V~~

~~PROCESSING STEPS POR THE AGPA PROCESS~~

5 Min. 1) Develop in Kodak D-19 2 Min. 2) Stop Bath 5 Min. 3) Rinse in Distilled Water 2 Min. 4) Bleach 5 Min. 5) Rinse in Distilled Water 1 Min. 6) Clear 5 Min. 7) Rinse in Distilled Water 10 Min. 8) Desensitize 9) Rinse Briefly in Ethyl Alcohol and Air Dry

~~BLEACH Potassium Bichromate...... 5 grams Concentrated Sulfuric Acid . . . 5 milliliters Distilled W a t e r ...... 1 liter~~

~~CLEARER Sodium Sulphite ...... 50 grams Sodium Hydroxide 1 gram Distilled Water ...... 1 liter~~

~~DE SENSITIZER Ethyl Alcohol ...... 88 percent Distilled Water ...... 10 percent Glycerol 2 percent Potassium Bromide.....•• 120 milligrams/liter Phenosafranine...... 200 milligrams/liter~~

~~102~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX VI~~

~~PROCESSING STEPS FOR THE DEEBY PROCESS~~

5 Min. 1) Develop in Kodak D-19 15 Sec. 2) Stop Bath 3 Min. 3) Fix in Kodak Rapid Fixer 5 Min. 4) Rinse in Distilled Water 7 Min. 5) Bleach 5 Min. 6) Rinse in Distilled Water 5 Min. 7) Clear 5 Min. 8) Rinse in Distilled Water 10 Min. 9) Desensitize 5 Sec. 10) Rinse in Ethyl Alcohol 11) Dry Slowly at Room Temperature

~~BLEACH Ferrous Chloride...... 25 grams Cuprous Bromide ...... 25 grams Concentrated Sulfuric Acid .. . 15 milliliters Distilled Water 500 milliliters~~

~~CLEARER Tetramethylammonium Iodide . . . 2 grams Distilled W a t e r ...... 1 liter~~

DESENSITIZER Ethyl Alcohol ...... 0.9 liter Distilled W a t e r ...... 0.1 liter Phenosafranine • 200 milligrams ( The process can he modified to delete steps 7 and 8 or step 9 without detrimental effects to the processed holograms )

~~103~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX YII PROCESSING STEPS FOR THE MARKHAM PROCESS~~

5 Min. 1) Develop in The Modified Developer 5 Min. 2) Rinse in Distilled Water 3) Re-expose Uniformly to White Light (Approximately 15 sec. to a 15-W hulh at 1 meter for Kodak 64-9-F plates and approximately .5 sec. to a 25-W bulh at 4 feet for Agfa-Gevaert 10E70 film) 5 Min. 4) Redevelop in The Modified Developer 5 Min. 5) Rinse in Distilled Water 5 Min. 6) Bleach 5 I n . 7) Rinse in Distilled Water 5 Min. 8) Clear 5 Min. 9) Rinse in Distilled Water 10 Min. 10) Desensitize 5 Sec. 11) Rinse in Ethyl Alcohol 12) Dry Slowly at Room Temperature

~~THE MODIFIED DEVELOPER Kodak D - 1 9 ...... 1 liter Sodium T h i o s u l p h a t e 0.5 gram~~

~~BLEACH Potassium Bichromate...... 8 grams Concentrated Sulfuric Acid . . . 10 milliliters Distilled Water 1 liter~~

~~CLEARER Tetramethylammonium Iodide . . . 2 grams Distilled Water • 1 liter~~

~~DESENSITIZER Ethyl Alcohol ...... 0.9 liter Distilled Water 0.1 liter Phenosafranine ...... 200 milligrams~~

~~10A~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX VIII INFORMATION ABOUT UNUSUAL CHEMICALS USED IN THIS PAPER~~

~~Phenosafranine (3,7-diamino-5-phenylphenazinium chloride) M.W. 322.80 3-NH2C6H5N:C6H3-7-KH2:N-5-C6H5Cl~~

~~Phenosaf ranine is a red dye used mostly for "biological staining 5~~

~~Tetramethylammonium Iodide M.W. 201.05 (CH3)4NI Tetramethylammonium is a strong electrolyte in solution oAh U a. ctt3-iN/-cH3 |~~

~~______0 ^ 3 ______Pyrocatechol (Catechol), (1,2-benzenediol) M.W. 110.11 CgH^-1,2-(OH)2~~

Pyrocatechol provides a strong tanning action on photographic gelatin due to its high value of pH. &-OH Xylene (1,2-dimethyl-benzene) or (1,3-dimethy1-benzene) or (1,4-dimethy1-benzene) M.W. 106.17 CgH^(CH3)2 “d :u5027 5°' .ob ob i . « t o (.) X X nD 1.4954 (p) ^ U* Co) C*0 (p)c*-b Xylene is used as a solvent as well as a starter for other organic compounds

~~105~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 106~~

~~APPENDIX YIII (Cont.)~~

~~Methyl Benzoate (Niobia Oil) M.W. 136.15 (C6H5C02CH5) nD 1.5162 QT~~

~~Methyl Benzoate is used as a solvent, a starter for other organic compounds, and also used in perfumery~~

Chiorobenzene M.W. 112.56 C6H5C1 nD 1.5236 U*

~~Chlorobenzene is used as a solvent as well as a starter for other organic compounds~~

1.2—Dibromopropane (propylene dibromide) M.W. 201.90 CH,CHBrCH0Br rt H H ? d t \ l „ nD 1.5190 H-C-C-C-Br H Br « 1.2-Dibromopropane is used as a solvent as well as a starter for other organic compounds

~~1 .3—Dibromopropane . ^ M.W. 201.90 Br(CH9),Br *1 V i 25 Br-C-C-C-Br n D 1 • 5214 H H H 1.3-Dibromopropane is used as a solvent as well as a starter for other organic compounds~~

~~Bromoethane (Ethyl Bromide) ^ ^ M.W. 108.97 C^Br «-U-8r~~

~~nD 1.9236 H-j|.~~

~~Bromoethane is used as a solvent as well as a starter for other organic compounds~~

~~. -j, 1~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.' ' 107~~

~~APPENDIX VIII (Cont.) C*3 p-Chlorotoulene M.W. 126.59 CH5C6H4C1 £ 0~~

~~nD 1.5150~~

~~p-Chlorotoulene is used as a solvent as well as a starter for other organic compounds~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. FOOTNOTES~~

1. Gabor, D., “A New Microscopic Principle." Nature, CLXI, (19^8), 777-778. 2. Leith, Emmett N., and Upatnieks, Juris, "Wavefront Reconstruction with Diffused Illumination and Three- Dimensional Objects." Journal of the Optical Society of America. LIY, lo. ll'; OTovember, 1'9U), 1295-1301. 3. Cathey, Jr., W.T., "Three-Dimensional Wavefront Recon struction Using a Fhase Hologram." Journal of the Optical Society of America, LV, No. 4, (April, 1965), 55TI 4. Leith and Upatnieks, 9p. cit. 5. Cathey, op. cit. 6. ibid. 7. Colburn, W.S., Zech, R.G. , rjiO Ralston, L.M., "Holo graphic Optical Elements." Government Technical Re port, No. AFAL-TR-72-409, Harris Electro-Optics Cen ter of Radiation, Ann Arbor, Michigan, (November, 1972), 44—61. 8. Shanhoff, T.A., "Phase Holograms in Dichromated Gel atin." Applied Optics, YII, No. 10, (October, 1968), 2101-21U5. 9. Lin, L.H., "Hologram Formation in Hardened Dichroma ted Gelatin Films." Applied Optics, VIII, No. 5, (May, 1969), 963-9667^ 10. Curran, R.K., and Shankoff, T.A., "The Mechanism of Hologram Formation in Dichromated Gelatin." Applied Optics, XI, No. 7, (July, 1970), 1651-1657. 11. Chang, Milton, "Dichromated Gelatin of Improved Opt ical Quality." Applied Optics, X, No. 11, (November, 1971), 2550-2551T 12. Colburn, Zech, and Ralston, op. cit., p. 61-78. 13. Close, D.H., Jacobson, A.D., Margerum, J.D., Brault, R.G., and McClung, F.J., "Hologram Recordings on Photopolymer Materials." Applied Physics Letters, XIV, No. 5, (1971), 2550-o 5T7 14. Jenney, J.A., "Holographic Recording with Photopoly mer." Journal of the Optical Society of America, LX, No. 9, (September, 197& j , n Z Y - T K T . ------15. Wopschall, R.H., "Dry Photopolymer Film for Record ing Holograms." Journal of the Optical Society of America, LXI, No. 5, IMay, 1971), b4-9.

~~108~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 109 16. Colburn, W.S., and Haines, X.A., "Volume Hologram Formation in Photopolymer Materials." Applied Optics, X, No. 7, (July, 1971), 1636-1641. 17. Colburn, Zech, and Ralston, op. cit., p. 78-95. 18. Tomlinson, W.J., Kaminow, I.P., Chandross, E.A., Pork, H.L., and Silvast, J., "Photoinduced Refracti ve Index Increase in Poly(Methyl Methacrylate) and its Applications." Applied Physics Letters, XVI, No. 12, (June, 1970), 486-489. 19. Colburn, Zech, and Ralston, op. cit., p. 95-108. 20. Sheridan, N.X., "Production of blazed Holograms." Applied Physics Letters, XII, No. 9, (May, 1968), 316-318. 21. Eartolini, R., Hannan, W., Xarlsons, P., and Lurie, M., "Embossed Hologram Motion Pictures for Televis ion Playback." Applied Optics, IX, No. 10, (October, 1970), 2283-229^7 22. Beesley, M.J., and Castledine, J.G., "The Use of Pho toresist as a Holographic Recording Medium." Applied Optics, IX, No. 12, (December, 1970), 2720-2724. 23 Bartolini, Robert A., "Improved Development for Hol ograms Recorded in Photoresist." Journal of the Opt- ical Society of America, XI, No. 5, (iMay, 1972),

24. Bartolini, Robert A., "Recording of Relief-Phase hol ograms in Photoresist." Journal of the Optical Socie ty of America, LXII, No. 11, ^November, 1972), 1397. 25. Colburn, Zech, and Ralston, op. cit., p. 109-126. 26. Sinclair, Yf.R., Sullivan, M.V., and Pastnacht, R.A., "DC Sputtered Films." Journal of the Electrochemical Society, CXVIII, (1971), 341. 27. Colburn, Zech, and Ralston, op. cit., p. 126-141. 28. Urbach, John C., and Meier, Reinhard W., "Thermoplas tic Xerographic Holography." Applied Optics, V, No. 4, (April, 1966), 666-667. 29. Lin, L.H., and Beauchamp, M.L., "Write-Read-Erase in Situ Optical Memory Using Thermoplastic Holograms." Applied Optics, IX, No. 9, (September, 1970), 2088-

~~30. Colburn, Zech, and Ralston, op. cit., p. 44-61. 31. loc. cit., p. 61-78. 32. loc. cit., p. 78-95. 33. loc. cit., p. 95-108.~~

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34. loc. cit., p. 109-126. 35. loc. cit., p. 126-141. 36. Burekhardt, C.B., “Efficiency of a Dielectric Grat ing. " Journal of the Optical Society of America. LVII, So. 3 7 " ® y 7 l9 6 7 ), 661-603. ------' 37. Latta, John H . , “The Bleaching of Holographic Diffr action Gratings for Maximum Efficiency." Applied Op tics, 711, No. 12, (December, 1968), 2409-24T6'. 38. Upatnieks, Juris, and Leonard, Carl, "Diffraction Efficiency of Bleached Photographically Recorded Interference Patterns." Applied Optics, VIII, No. 1, (January, 1969), 85-89. 39. Cenco Model No. 87288, Central Scientific Company, 2600 South Kostner Avenue, Chicago, Illinois, 60623. 40. Jarrell-Ash Company Scientific Instruments, no. L451.309/57550, Newtonville 60, Massachusetts. 41. Colburn, Zech, and Ralston, op. cit., p. 12-44. 42. Lamberts, R.L., and Kurtz, C.N., “Reversal Bleaching for Low Plare Light in Holograms." Applied Optics, X, No. 6, (June, 1971), 1342-1347. 43. Hariharan, P., Kaushik, G.S., and Ramanathan, C.S., "Simplified, Low Noise Processing Technique for Photographic Phase Holograms." Optics Coanunications VI, No. 1, (September, 1972), 75-76. 44. Hariharan, P., and Ramanathan, C.S., "Supression of Printout Effect in Photographic Phase Holograms." Applied Optics, X, No. 9, (September, 1971), 2197-

45. Processing technique for producing phase holograms, Agfa-Gevaert, Inc., 275 North Street, Teterboro, New Jersey. 46. Lehmann, M., Lauer, J.P., and Goodman, J.W., "High Efficiency, Low Noise, and Suppression of Photochr- omic Effects in Bleached Silver Halide Photography." Applied Optics, IX, No. 8, (August, 1970), 1948-1949 47. loc. cit., p. 1948. 48. Upatnieks, Juris, and Leonard, Carl, "Efficiency and Image Contrast of Dielectric Holograms." Journal of the Optical Society of America, LX, No. 3, (March, 1970), 305. 49. Lehmann, Lauer, and Goodman, op. cit., p. 1948. 50. ibid.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. I l l~~

5 1 . McMahon, D.H., and Mai one j, W.F., "Measurements of the Stability of Bleached Photographic Phase Holo grams." Applied Optics, IX, No. 6, (June, 1970), 1363-1365. 52. Colburn, Zech, and Balston, op. cit., p. 12-44. 53. Lamberts and Kurtz, op. cit. 54. , Eastman Organic Chemicals Catalog No. 47, Kodak Publication No. JJ-1, Eastman Kodak Company! Eastman Organic Chemicals, Rochester, New York, 14650, (May 31, 1974), 187. Catalog chemical No. P604, Price: 100 g - S3.90; 500 g - $9.50. 55. Lamberts and Kurtz, op. cit., p. 1347. 56. Agfa-Gevaert, Inc., 275 North Street, Teterboro, New Jersey. 57. , Kodak Plates and Fijjns for Science and Industry, 1st, ea., Kodak Pamphlet No. P-9> Eastman Kodak Company, Rochester, New York, 14650, (1967), 4d, lOd. 58. Hariharan, P., Kaushik, G.S., and Ramanathan, C.S., op. cit. 59. Altman, J.H., "Pure Relief Images on Type 649-F Pla tes." Applied Optics, V, No. 10, (October, 1966), 1689-15901 60. Russo, V., and Sottini, S., "Bleached Holograms." Applied Optics, VII, No. 1, (January, 1968), 202. 61. McMahon, D.H., and Franklin, A.R., "Efficient, High Quality R-10 Bleached Holographic Diffraction Grat ings." Applied Optics. VIII, No. 9, (September, 1969)» 1927-1929. 62. Upatnieks, Juris, and Leonard, Carl, "Diffraction Efficiency of Bleached Photographically Recorded Interference Patterns," op. cit. 63. McMahon and Maloney, op. cit. 64. McMahon and Franklin, op. cit., p. 1929. 65. Upatnieks and Leonard, op. cit., p. 86. 66. McMahon and Maloney, op. cit. 67. loc. cit., p. 1367. 68. Hariharan and Ramanathan, op. cit., p. 2197-2198. 69. Hariharan, P., Ramanathan, C.S., and Kaushik, G.S., "Simplified Processing Technique for Photographic Phase Holograms." Optics Communications, III, No. 4, (June, 1971), 246.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 112 70. Hariharan, P., Kaushik, G.S., and Ramanathan, C.S., "Seduction of Scattering in Photographic Phase Holo grams." Optics Communications, V, Ho. 1, (April, 1972), 5T. ------71. Hariharan, P., "Reversal Processing Technique for Phase Holograms." Optics Communications, III, No. 2, (April, 1971), 1 1 9 . ------72. Hariharan and Ramanathan, op. cit., p. 2197-2199. 73. loc. cit., p. 2198. 74. , Eastman Organic Chemicals Catalog No. 47, Kodak Publication No. JJ-1, Eastman Kodak Company” Eastman Organic Chemicals, Rochester, New York, 14650, (May 31, 1974), 201. Catalog chemical No. 2434, Price: 100 g - $11.95; 500 g - $47.40. 75. Processing technique for producing phase holograms, Agfa-Gevaert, Inc., 275 North Street, Teterboro, New Jersey. 76. ______, Eastman Organic Chemicals Catalog No. 47, Kodak Publication No. JJ-1, Eastman Kodak Company, Eastman Organic Chemicals, Rochester, New York, 14650, (May 51, 1974), 174. Catalog chemical No. 1125, Price: 100 g - $49.45; 25 g - $14.35. 77. Hees, C.E. Kenneth, and James, T.H., The Theory of the Photographic Process, 3rd. ed., New ^ork: The Mac iiillan Company, (19&6), 231 citing (a) LUppo-Cramer, Z., Angew. Chem., 40, 1225, (1927); (b) Phot. Korr., 57, 311, (1920); (c) in J.M. Eder, Ausftthrliches Handbuch der Photographie, Vol. 3, 3rd. ed., Part 3, W. Knapp, Halle, 1932, p. 275. 78. Chang, Milton, and George, Nicholas, "Holographic Dielectric Grating: Theory and Practice." Applied Optics. IX, No. 3, (March, 1970), 718. 79. Type No. SEC-48, AB26, Serial No. 201312, Bendix Corporation, Pioneer Central Division, Davenport, Iowa. 80. , Kodak Plates and Pilms for Science and Industry, 1st. ed., Kodak Pamphlet No. P-9, Eastman Kodak Company, Rochester, New York, 14650, (1967), 7d, lid. 81. No. E, 498.305/42328, Jarrell-Ash Company Optical Instruments, Boston, Massachusetts. 82. Colburn, Zech, and Ralston, op. cit., p. 16. 83. Latta, op. cit., p. 2413. 84. Lamberts and Kurtz, op. cit., p. 1343.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. — 113 35. Upatnieks and Leonard, "Efficiency and Image Contrast of Dielectric Holograms," op. cit. 86. Young, M. , and Kittridge, F.H., "Amplitude and Phase Holograms Exposed on Agfa-Gevaert 10E75 Plates." Applied Optics. VIII, Ho. 11, (November, 1969), 2354. 87. Upatnieks, Juris, and Leonard, Carl, "Signal and Noi se in Bleached Holograms." Journal of the Optical Society of America, LIX, No. 4, (April, 1969)* 481. 88. Kurtz, C.N., and Edgett, C.D., "Flare Light in Blea ched Holograms." Journal of the Optical Society of America, LIX, No. ll, November, 1969)» 1545. 89. , Eastman Organic Chemicals Catalog No. 47, Kodak Publication ifo. jJ-1, Eastman Kodak Company, Eastman Organic Chemicals, Rochester, New York, 14650, (May 31, 1974), 226. Catalog chemical No. P460, Price: 250 g - 84.45; 1 kg. - 87.50. 90. loc. cit., p. 146. Catalog chemical No. 317, Price: 500 g - 85.45; 3 kg. -818.10. 91. loc. cit., p. 57, Catalog chemical No. 70, Price: 1 kg. - 84.30; 4 kg. - $10.40, 5 gal. - $23.45. 92. loc. cit., p. 42, Catalog chemical No. 114, Price: 250 g - $9.00; 1 kg. - §25.55. 93. loc. cit., p. 64, Catalog chemical No. 74, Price: 500 g - $4.75; 4 kg. - $21.15. 94. loc. cit., p. 77, Catalog chemical No. 1277, Price: 100 g - $10.15; 500 g - $37.95. 95. loc. cit., Catalog chemical No. 261, Price: 100 g - $8.75; 250 g - $17.55.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. BIBLIOGRAPHY~~

~~Books:~~

Caulfield, H.J., and Lu, Sun, The Applications of Holog raphy, 1st. ed., New York: Wiley-Interscience, 19*70. Jp. XIII + 138. Collier, Robert J., Burckhardt, Christoph B . , and Lin, Lawrence H. , Optical Holography, 1st. ed., New York: Academic Press, Inc., 1 9 V1 . Pp. XVII + 605. Mees, C.E. Kenneth, and James, T.H., The Theory of the Photographic Process, 3rd. ed., New York: The Macmillan Company, 1966. i*p. XI + 591. Smith, Howard M., Principles of Holography, 1st. ed., New York: Wiley-Interscience, 1969. Pp. Xll ♦ 239•

~~Periodicals:~~

Altman, J.H., "Pure Relief Images on Type 649-F Plates.” Applied Optics, V, No. 10, (October, 1966), 1689-1690. Bartolini, Robert A., "Improved Development for Holograms Recorded in Photoresist." Journal of the Optical Society of America. XI, No. 5, (May, 1972), 1275-1276. Bartolini, Robert A., "Recording of Relief-Phase Holograms in Photoresist." Journal of the Optical Society of America, LXII, No. 11, (November, 1972), 1397. Bartolini, R., Hannan, W . , Karlsons, D., and Lurie, M., "Embossed Hologram Motion Pictures for Television Play back." Applied Optics, IX, No. 10, (October, 1970), 2283- 2290. Beesley, M.J., and Castledine, J.G., "The Use of Photore sist as a Holographic Recording Medium." Applied Optics. IX, No. 12, (December, 1970), 2720-2724. Burckhardt, C.B., "Efficiency of a Dielectric Grating." Journal of the Optical Society of America, LVII, No. 5* (May, 1967), 601-603. Cathey, Jr., W.T., "Three-Dimensional Wavefront Reconstr uction Using a Phase Hologram." Journal of the Optical Society of America. LV, No. 4, (April, 1965), 457. Chang, Milton, "Bichromated Gelatin of Improved Optical Quality." Applied Optics, X, No. 11, (November, 1971), 2550-2551.

~~114~~

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. i~~

~~115~~

~~Periodicals (Cont.):~~

Chang, Hilton, and George, Nicholas, “Holographic Dielec tric Grating: Theory and Practice.* Applied Optics, IX, No. 3, (March, 1970), 713-719* Close, D.H., Jacobson, A.D., Margerum, J.D., Erault, R.G., and McClung, F.J., "Hologram Recordings bn Photopolymer Materials.- Applied Physics Letters, XIV, No. 5, (1971), 2550-2551. Colburn, W.S., and Haines, K.A., "Volume Hologram Format ion in Photopolymer Materials." Applied Optics, X, No. 7, (July, 1971), 1636-1641. Curran, R.K., and Shankoff, T.A., "The Mechanism of Holo gram Formation in Dichromated Gelatin." Applied Optics, XI, No. 7, (July, 1970), 1651-1657. Gabor, L. , "A New Microscopic Principle." Nature, CLXI, (1948), 777-778. Hariharan, P., "Reversal Processing Technique for Phase Holograms." Optics Communications, III, No. 2, (April, 1971), 119-121: Hariharan, P., Kaushik, G.S., and Hamanathan, C.S., "Red uction of Scattering in Photographic Phase Holograms." Optics Communications, V, No. 1, (April, 1972), 59-61. Hariharan, P., Raushik, G.S., and Hamanathan, C.S.,"Simp lified, Low Noise Processing Technique for Photographic Phase Holograms." Optics Communications, VI, No. 1, (Sept ember, 1972), 75-75: Hariharan, P., and Hamanathan, C.S., "Supression of Print out Effect in Photographic Phase Holograms." Applied Opti- cs, X, No. 9, (September, 1971), 2197-2199. Hariharan, P., Hamanathan, C.S., and Kaushik, G.S., "Simp lified Processing Technique for Photographic Phase Holo grams." Optics Communications, III, No. 4, (June, 1971), 246-247. Jenney, J.A., “Holographic Recording with Photopolymer." Journal of the Optical Society of America, LX, No. 9, (September, 1970), ll$5-ll6l. Kurtz, C.N., and Edgett, C.D., "Flare Light in Bleached Holograms." Journal of the Optical Society of America, LIX, No. 11, (November, i 9 W , 1544-1545T Lamberts, R.L., and Kurtz, C.N., “Reversal Bleaching for Low Flare Light in Holograms." Applied Optics, X, No. 6, (June, 1971), 1342-1347.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 116~~

~~Periodicals (Cont.):~~

Latta, John H., "The Bleaching of Holographic Diffraction Gratings for Maximum Efficiency." Applied Optics. VII. No. 12, (December, 1968), 2409-24157^------Lehmann, M. , Lauer, J.P., and Goodman, J.W., "High Effic iency, Low Noise, and Supression of Photochromic Effects in Bleached Silver Halide Photography." Applied Optics. IX, No. 8, (August, 1970), 1948-1949. ------Leith, Emmett N., and Upatnieks, Juris, "Photography by Laser." Scientific American, CCXII, No. 6, (June.'1965). 24-35. Leith, Emmett.N., and Upatnieks, Juris, "’wavefront Recon struction with Diffused Illumination and Three-Dimensional Objects." Journal of the Optical Society of America, LIV. No. 11, (November,' Y964), 1295-1301. Lin, L.H., "Hologram Formation in Hardened Dichromated Gelatin Films." Applied Optics, VIII, No. 5, (May, 1969). 963-966. Lin, L.H., and Beauchamp, M.L., "Write-Eead-Erase in Situ Optical Memory Using Thermoplastic Holograms." Applied Optics, IX, No. 9, (September, 1970), 2088-2092. McMahon, D.H., and Franklin, A.R., "Efficient, High Qual ity R-10 Bleached Holographic Diffraction Gratings." Applied Optics. VIII, No. 9* (September, 1969), 1927-1929. McMahon, D.H., and Maloney, W.F., "Measurements of the Stability of Bleached Photographic Phase Holograms." Applied Optics. IX, No. 6, (June, 1970), 1363-1368. Russo, V., and Sottini, S., "Bleached Holograms." Applied Optics. VII, No. 1, (January, 1968), 202. Shanhoff, T.A., "Phase Holograms in Dichromated Gelatin." Applied Optics. VII, No. 10, (October, 1968), 2101-2105. Sheridan, N.K., "Production of Blazed Holograms." Applied Physics Letters. XII, No. 9, (May, 1968), 316-318. Sinclair, V.R., Sullivan, M.V., and Fastnacht, R.A., "DC Sputtered Films." Journal of the Electrochemical Society. CXVIII, (1971), 5417 Tomlinson, V.J., Eaminow, I.P., Chandross, E.A., Fork, R.L., and Silvast, J., "Photoinduced Refractive Index Increase in Poly(Methyl Methacrylate) and its Applicat ions." Applied Physics Letters, XVI, No. 12, (June, 1970), 486-489.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 117~~

~~Periodicals (Cont.):~~

Upatnieks, Juris, and Leonard, Carl, "Diffraction Effic iency of Bleached Photographically Recorded Interference Patterns." Applied Optics. VIII, Ho. 1, (January, 1969), 85-89. Upatnieks, Juris, and Leonard, Carl, "Efficiency and Image Contrast of Dielectric Holograms." Journal of the Optical Society of America, LX, No. 3, (March, 1970), 297-305. Upatnieks, Juris, and Leonard, Carl, "Signal and Noise in Bleached Holograms." Journal of the Optical Society of America, LIX, No. 4, (April, 1969), 481-482. Urhach, John C., and Meier, Reinhard W., "thermoplastic Xerographic Holography." Applied Optics, V, No. 4, (April, 1966), 666-667. Wopschall, R.H., "Dry Photopolymer Film for Recording Holograms." Journal of the Optical Society of America, LXI, No. 5, (May, 1971), 649: ------Young, M . , and KLttridge, F.H., "Amplitude and Phase Hol ograms Exposed on Agfa-Gevaert 10E75 Plates." Applied Optics, VIII, No. 11, (November, 1969), 2353-2354^

~~Pamphlets:~~

, Eastman Organic Chemicals Catalog No. 47, Kodak Publication No. JJ-1, Eastman kodak Company, East man Organic Chemicals, Rochester, New York, 14650, (May 31, 1974), Pp. 322. , Kodak Plates and Films for Science and Indus try, 1 s t . ed., kodak Pamphlet No. P-§, Eastman Kodak Com- pany, Rochester, New York, 14650, (1967), Pp. 32 ♦ 44d.

~~Bulletin:~~

Colburn, W.S., Zech, R.G., and Ralston, L.M., Holographic Optical Elements, Government Technical Report, #o. AFAi- TR—72-409* Harris Electro-Optics Center of Radiation, Ann,Arbor, Michigan, (January, 1973), Pp. XI + 155.

~~Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.~~