DOCSLIB.ORG

502-20 Chromatic Effects

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

20-1 I and Instrumentation Design Optical OPTI-502 © Copyright 2019 John E. Greivenkamp E. John 2019 © Copyright Section 20 Chromatic Effects 20-2 I and Instrumentation Design Optical OPTI-502 Chromatic Aberration Greivenkamp E. John 2019 © Copyright For a thin lens: 1 nCC1 f 12 Since the index changes with wavelength, so will the focal length. z 1 2 3 Where do Red, Green (or Yellow) and Blue focus? n Because of the higher index for Blue or F light, Blue light is bent more and the Blue focus is closest to the lens. The foci corresponding to the F, d and C wavelengths are not evenly spaced due to the shape of the F d C dispersion curve. 20-3 I and Instrumentation Design Optical OPTI-502 Axial or Longitudinal Chromatic Aberration Greivenkamp E. John 2019 © Copyright Axial chromatic aberration or axial color is a variation of the system focal length with wavelength. FdC z f f = fd FC nCCnCC F 1112 C 12 nnCCFC12 11F C nn ffCF f FC nCCd 1 12 CF CF nd 1 ff f 2 n 1 CF 2 CF d d CF d ddnCC1 12 nnF C dd11f ffCF f 2 d dd FC 20-4 I and Instrumentation Design Optical OPTI-502 Axial Chromatic Aberration - Continued Greivenkamp E. John 2019 © Copyright FCf CF 1 d F cFC FC ddf f f ff f d f 1 CF CF ffCF f Since Abbe numbers are typically 30-70, the longitudinal chromatic aberration of a singlet is 1.5-3% of the focal length. The relative order of the foci is reversed for a negative lens. F focuses closest to the lens for both a positive and a negative lens. Longitudinal focus position: z from d focus Because of the flattening of the dispersion curve, the d-C F d C separation tends to be less than the F-d separation. 20-5 I and Instrumentation Design Optical OPTI-502 Axial Chromatic Aberration of a Negative Lens Greivenkamp E. John 2019 © Copyright For a negative lens, the Blue or F focus remains closest to the lens as Blue light has the largest ray bending. Of course all of the foci are virtual, but the order relative to the lens is the same for a negative or positive lens. F d C d F C z f f = fd The same relationships hold but now the quantities are negative: f 1 f 1 F cFC FC CF ddf f f ffCF f CF ffdd 00 f CFFC f 0 0 20-6 I and Instrumentation Design Optical OPTI-502 Axial or Longitudinal Chromatic Aberration Greivenkamp E. John 2019 © Copyright The blur associated with the chromatic aberration of the objective lens limits the performance of an objective. z Blur To reduce the blur, a small diameter objective lens is required. Since the longitudinal aberration f is constant for a given f, the blur is proportional to the lens diameter. z Blur 20-7 I and Instrumentation Design Optical OPTI-502 Transverse Axial Chromatic Aberration Greivenkamp E. John 2019 © Copyright Transverse axial chromatic aberration measures the image blur size due to axial chromatic aberration. TA rP CH z f f f f The rays from the edge of the pupil are approximately parallel in the vicinity of the focus. Remember that the axial chromatic is 1.5-3% of the focal length and that the diagram is greatly exaggerated. 20-8 I and Instrumentation Design Optical OPTI-502 Transverse Axial Chromatic Aberration Greivenkamp E. John 2019 © Copyright Transverse axial chromatic aberration measures the image blur size due to axial chromatic aberration. Because f f , the three marginal rays (F, d and C) are approximately parallel. Rays from edge of pupil TA TA tanU CH CH f z r U tanU P FdC f f TA r CH P ff TA f 1 TA depends only on the glass and the pupil CH CH radius r (assumes that the stop is at the lens). rfP P r TA P CH 20-9 I and Instrumentation Design Optical OPTI-502 Transverse Axial Chromatic Aberration – Alternate Derrivation Greivenkamp E. John 2019 © Copyright Consider the edge of the lens to be a thin prism of Abbe Number with a deviation and a dispersion . ,0 r P TACH z f rP rP Blur TACH f f f r Blur TAP f CH f The blur is the product of the dispersion and the focal length. rP TACH The ray deviation and dispersion grow as the pupil radius normalized by the focal length. The net result is independent of the focal length. 20-10 I and Instrumentation Design Optical OPTI-502 Lateral Chromatic Aberration Greivenkamp E. John 2019 © Copyright Longitudinal chromatic aberration is chromatic aberration of the marginal ray of the system. Lateral chromatic aberration or lateral color is caused by dispersion of the chief ray. C d F z Stop Image Plane The edge of the lens behaves like a prism. Off-axis image points will exhibit a radial color smear. The blur length increases linearly with image height. Each color has a different lateral magnification. 20-11 I and Instrumentation Design Optical OPTI-502 Achromatic Objective or Doublet Greivenkamp E. John 2019 © Copyright Two lens elements with different dispersive properties are combined into a single objective lens. Red and blue light are made to focus at the same location and a greatly reduced image blur results even with large diameter lenses. z Blur Crown Flint 20-12 I and Instrumentation Design Optical OPTI-502 Achromatic Doublet Greivenkamp E. John 2019 © Copyright The thin lens achromatic doublet corrects longitudinal chromatic aberration by combining a positive thin lens and a negative thin lens. Two different glasses (1, P1 and 2, P2 ) are used. The nominal powers and focal lengths are for d light. 12 12, at d FCFCFC12 For each lens: 1 di i 12 FCi FC ii 12 2 Achromat: FC F C 0 12 11 12 12 ,,12 at d 2 21 22 1 12 2 121 1 1 20-13 I and Instrumentation Design Optical OPTI-502 Secondary Chromatic Aberration Greivenkamp E. John 2019 © Copyright The solution for the thin lens achromatic doublet result forces the same axial focus for F and C light (zero primary chromatic aberration), but d light can focus at a different location. This residual is the secondary chromatic aberration or secondary color of the doublet. dC d C f Cd ff C d nCCnCC11 dC dC12 dC dC11 d 121 C 12 dC11112 nnCC d C dCPP1122 FC FC nndC11 dC11112nnCC F C 12 nn dC PP12 FC11 12 nn 12 dC11 For an achromat: P1 FC11112 nnCC F C 12 nnFC11 PP 1 P 1 dC 12 dC11 FC 1 FC1 1 1 and 11 1 12 1 12 P 2 dC22 FC 2 FC 2 2 PP12 P dC 12 20-14 I and Instrumentation Design Optical OPTI-502 Secondary Chromatic Aberration or Secondary Color Greivenkamp E. John 2019 © Copyright dC f Cd PP21 P dC d C f Cd fff2 C d f 21 dF-C z f = fd fCd Focus shift from d ff d fCd FdC The d focus is probably not the maximum focus shift from F and C. 20-15 I and Instrumentation Design Optical OPTI-502 Partial Dispersion Ratio and the Abbe Number Greivenkamp E. John 2019 © Copyright On a plot of P versus , most glasses lie on a straight line. P nndC PPdC, nnF C n 1 d nnF C P 1 The slope of this line is approximately: 0.00045 2200 Example: BK7 = 64.17 P = .3075 F2 = 36.37 P = .2937 P .0138 1 .0005 27.80 2014 20-16 I and Instrumentation Design Optical OPTI-502 P versus – Real Glass Data Greivenkamp E. John 2019 © Copyright Data for all of the glasses in the Schott Glass Catalog: 0.3200 d,C P 0.3100 0.3000 Partial Dispersion Ratio Partial Dispersion 0.2900 0.2800 0.00 25.00 50.00 75.00 Abbe Number 20-17 I and Instrumentation Design Optical OPTI-502 Singlet versus Doublet Performance Greivenkamp E. John 2019 © Copyright Singlet: fCF 1 f fffCF C F fd 30 70 f Primary chromatic f CF 50 aberration of a singlet. fPCd Doublet: fCdff C d f P 1 0.00045 2200 f Secondary chromatic fCd 2200 aberration of a doublet. The use of the achromatic doublet reduces chromatic focal length variation by a factor of about 40 over the same focal length singlet. 20-18 I and Instrumentation Design Optical OPTI-502 Excess Power Greivenkamp E. John 2019 © Copyright The doublet design places excess power in the positive element that is cancelled by the negative element. Both elements contribute equal, but opposite, amounts of longitudinal chromatic aberration. Just as with the achromatic thin prism, the longitudinal chromatic aberration grows slower with the low dispersion glass (positive element) than the high dispersion glass (negative element). Large differences in the Abbe numbers minimize the excess power and provide better performance. Large Small 20-19 I and Instrumentation Design Optical OPTI-502 Zero Secondary Color Greivenkamp E. John 2019 © Copyright In order to obtain zero secondary chromatic aberration with a doublet, the partial dispersion ratios of the two glasses must be zero. P Pff00 Cd There are some special glass pairs which have different Abbe numbers but the same partial dispersion ratio. Unfortunately, the difference in Abbe number is usually small, resulting in an achromatic doublet with significant excess power. To correct chromatic aberration at additional wavelengths more than two glasses are used: Apochromat – 3 glasses with correction at three wavelengths.
Recommended publications
  • Panoramas Shoot with the Camera Positioned Vertically As This Will Give the Photo Merging Software More Wriggle-Room in Merging the Images

    Panoramas Shoot with the Camera Positioned Vertically As This Will Give the Photo Merging Software More Wriggle-Room in Merging the Images

    P a n o r a m a s What is a Panorama? A panoramic photo covers a larger field of view than a “normal” photograph. In general if the aspect ratio is 2 to 1 or greater then it’s classified as a panoramic photo. This sample is about 3 times wider than tall, an aspect ratio of 3 to 1. What is a Panorama? A panorama is not limited to horizontal shots only. Vertical images are also an option. How is a Panorama Made? Panoramic photos are created by taking a series of overlapping photos and merging them together using software. Why Not Just Crop a Photo? • Making a panorama by cropping deletes a lot of data from the image. • That’s not a problem if you are just going to view it in a small format or at a low resolution. • However, if you want to print the image in a large format the loss of data will limit the size and quality that can be made. Get a Really Wide Angle Lens? • A wide-angle lens still may not be wide enough to capture the whole scene in a single shot. Sometime you just can’t get back far enough. • Photos taken with a wide-angle lens can exhibit undesirable lens distortion. • Lens cost, an auto focus 14mm f/2.8 lens can set you back $1,800 plus. What Lens to Use? • A standard lens works very well for taking panoramic photos. • You get minimal lens distortion, resulting in more realistic panoramic photos. • Choose a lens or focal length on a zoom lens of between 35mm and 80mm.
  • Chapter 3 (Aberrations)

    Chapter 3 (Aberrations)

    Chapter 3 Aberrations 3.1 Introduction In Chap. 2 we discussed the image-forming characteristics of optical systems, but we limited our consideration to an infinitesimal thread- like region about the optical axis called the paraxial region. In this chapter we will consider, in general terms, the behavior of lenses with finite apertures and fields of view. It has been pointed out that well- corrected optical systems behave nearly according to the rules of paraxial imagery given in Chap. 2. This is another way of stating that a lens without aberrations forms an image of the size and in the loca- tion given by the equations for the paraxial or first-order region. We shall measure the aberrations by the amount by which rays miss the paraxial image point. It can be seen that aberrations may be determined by calculating the location of the paraxial image of an object point and then tracing a large number of rays (by the exact trigonometrical ray-tracing equa- tions of Chap. 10) to determine the amounts by which the rays depart from the paraxial image point. Stated this baldly, the mathematical determination of the aberrations of a lens which covered any reason- able field at a real aperture would seem a formidable task, involving an almost infinite amount of labor. However, by classifying the various types of image faults and by understanding the behavior of each type, the work of determining the aberrations of a lens system can be sim- plified greatly, since only a few rays need be traced to evaluate each aberration; thus the problem assumes more manageable proportions.
  • A N E W E R a I N O P T I

    A N E W E R a I N O P T I

    A NEW ERA IN OPTICS EXPERIENCE AN UNPRECEDENTED LEVEL OF PERFORMANCE NIKKOR Z Lens Category Map New-dimensional S-Line Other lenses optical performance realized NIKKOR Z NIKKOR Z NIKKOR Z Lenses other than the with the Z mount 14-30mm f/4 S 24-70mm f/2.8 S 24-70mm f/4 S S-Line series will be announced at a later date. NIKKOR Z 58mm f/0.95 S Noct The title of the S-Line is reserved only for NIKKOR Z lenses that have cleared newly NIKKOR Z NIKKOR Z established standards in design principles and quality control that are even stricter 35mm f/1.8 S 50mm f/1.8 S than Nikon’s conventional standards. The “S” can be read as representing words such as “Superior”, “Special” and “Sophisticated.” Top of the S-Line model: the culmination Versatile lenses offering a new dimension Well-balanced, of the NIKKOR quest for groundbreaking in optical performance high-performance lenses Whichever model you choose, every S-Line lens achieves richly detailed image expression optical performance These lenses bring a higher level of These lenses strike an optimum delivering a sense of reality in both still shooting and movie creation. It offers a new This lens has the ability to depict subjects imaging power, achieving superior balance between advanced in ways that have never been seen reproduction with high resolution even at functionality, compactness dimension in optical performance, including overwhelming resolution, bringing fresh before, including by rendering them with the periphery of the image, and utilizing and cost effectiveness, while an extremely shallow depth of field.
  • Ground-Based Photographic Monitoring

    Ground-Based Photographic Monitoring

    United States Department of Agriculture Ground-Based Forest Service Pacific Northwest Research Station Photographic General Technical Report PNW-GTR-503 Monitoring May 2001 Frederick C. Hall Author Frederick C. Hall is senior plant ecologist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Region, Natural Resources, P.O. Box 3623, Portland, Oregon 97208-3623. Paper prepared in cooperation with the Pacific Northwest Region. Abstract Hall, Frederick C. 2001 Ground-based photographic monitoring. Gen. Tech. Rep. PNW-GTR-503. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 340 p. Land management professionals (foresters, wildlife biologists, range managers, and land managers such as ranchers and forest land owners) often have need to evaluate their management activities. Photographic monitoring is a fast, simple, and effective way to determine if changes made to an area have been successful. Ground-based photo monitoring means using photographs taken at a specific site to monitor conditions or change. It may be divided into two systems: (1) comparison photos, whereby a photograph is used to compare a known condition with field conditions to estimate some parameter of the field condition; and (2) repeat photo- graphs, whereby several pictures are taken of the same tract of ground over time to detect change. Comparison systems deal with fuel loading, herbage utilization, and public reaction to scenery. Repeat photography is discussed in relation to land- scape, remote, and site-specific systems. Critical attributes of repeat photography are (1) maps to find the sampling location and of the photo monitoring layout; (2) documentation of the monitoring system to include purpose, camera and film, w e a t h e r, season, sampling technique, and equipment; and (3) precise replication of photographs.
  • Tessar and Dagor Lenses

    Tessar and Dagor Lenses

    Tessar and Dagor lenses Lens Design OPTI 517 Prof. Jose Sasian Important basic lens forms Petzval DB Gauss Cooke Triplet little stress Stressed with Stressed with Low high-order Prof. Jose Sasian high high-order aberrations aberrations Measuring lens sensitivity to surface tilts 1 u 1 2 u W131 AB y W222 B y 2 n 2 n 2 2 1 1 1 1 u 1 1 1 u as B y cs A y 1 m Bstop ystop n'u' n 1 m ystop n'u' n CS cs 2 AS as 2 j j Prof. Jose Sasian Lens sensitivity comparison Coma sensitivity 0.32 Astigmatism sensitivity 0.27 Coma sensitivity 2.87 Astigmatism sensitivity 0.92 Coma sensitivity 0.99 Astigmatism sensitivity 0.18 Prof. Jose Sasian Actual tough and easy to align designs Off-the-shelf relay at F/6 Coma sensitivity 0.54 Astigmatism sensitivity 0.78 Coma sensitivity 0.14 Astigmatism sensitivity 0.21 Improper opto-mechanics leads to tough alignment Prof. Jose Sasian Tessar lens • More degrees of freedom • Can be thought of as a re-optimization of the PROTAR • Sharper than Cooke triplet (low index) • Compactness • Tessar, greek, four • 1902, Paul Rudolph • New achromat reduces lens stress Prof. Jose Sasian Tessar • The front component has very little power and acts as a corrector of the rear component new achromat • The cemented interface of the new achromat: 1) reduces zonal spherical aberration, 2) reduces oblique spherical aberration, 3) reduces zonal astigmatism • It is a compact lens Prof. Jose Sasian Merte’s Patent of 1932 Faster Tessar lens F/5.6 Prof.
  • Applied Physics I Subject Code: PHY-106 Set: a Section: …………………………

    Applied Physics I Subject Code: PHY-106 Set: a Section: …………………………

    Test-1 Subject: Applied Physics I Subject Code: PHY-106 Set: A Section: ………………………….. Max. Marks: 30 Registration Number: ……………… Max. Time: 45min Roll Number: ………………………. Question 1. Define systematic and random errors. (5) Question 2. In an experiment in determining the density of a rectangular block, the dimensions of the block are measured with a vernier caliper with least count of 0.01 cm and its mass is measured with a beam balance of least count 0.1 g, l = 5.12 cm, b = 2.56 cm, t = 0.37 cm and m = 39.3 g. Report correctly the density of the block. (10) Question 3. Derive a relation to overcome chromatic aberration for an optical system consisting of two convex lenses. (5) Question 4. An achromatic doublet of focal length 20 cm is to be made by placing a convex lens of borosilicate crown glass in contact with a diverging lens of dense flint glass. Assuming nr = 1.51462, nb = ′ ′ 1.52264, 푛푟 = 1.61216, and 푛푏 = 1.62901, calculate the focal length of each lens; here the unprimed and the primed quantities refer to the borosilicate crown glass and dense flint glass, respectively. (10) Test-1 Subject: Applied Physics I Subject Code: PHY-106 Set: B Section: ………………………….. Max. Marks: 30 Registration Number: ……………… Max. Time: 45min Roll Number: ………………………. Question 1. Distinguish accuracy and precision with example. (5) Question 2. Obtain an expression for chromatic aberration in the image formed by paraxial rays. (5) Question 3. It is required to find the volume of a rectangular block. A vernier caliper is used to measure the length, width and height of the block.
  • Carl Zeiss Oberkochen Large Format Lenses 1950-1972

    Carl Zeiss Oberkochen Large Format Lenses 1950-1972

    Large format lenses from Carl Zeiss Oberkochen 1950-1972 © 2013-2019 Arne Cröll – All Rights Reserved (this version is from October 4, 2019) Carl Zeiss Jena and Carl Zeiss Oberkochen Before and during WWII, the Carl Zeiss company in Jena was one of the largest optics manufacturers in Germany. They produced a variety of lenses suitable for large format (LF) photography, including the well- known Tessars and Protars in several series, but also process lenses and aerial lenses. The Zeiss-Ikon sister company in Dresden manufactured a range of large format cameras, such as the Zeiss “Ideal”, “Maximar”, Tropen-Adoro”, and “Juwel” (Jewel); the latter camera, in the 3¼” x 4¼” size, was used by Ansel Adams for some time. At the end of World War II, the German state of Thuringia, where Jena is located, was under the control of British and American troops. However, the Yalta Conference agreement placed it under Soviet control shortly thereafter. Just before the US command handed the administration of Thuringia over to the Soviet Army, American troops moved a considerable part of the leading management and research staff of Carl Zeiss Jena and the sister company Schott glass to Heidenheim near Stuttgart, 126 people in all [1]. They immediately started to look for a suitable place for a new factory and found it in the small town of Oberkochen, just 20km from Heidenheim. This led to the foundation of the company “Opton Optische Werke” in Oberkochen, West Germany, on Oct. 30, 1946, initially as a full subsidiary of the original factory in Jena.
  • AG-AF100 28Mm Wide Lens

    AG-AF100 28Mm Wide Lens

    Contents 1. What change when you use the different imager size camera? 1. What happens? 2. Focal Length 2. Iris (F Stop) 3. Flange Back Adjustment 2. Why Bokeh occurs? 1. F Stop 2. Circle of confusion diameter limit 3. Airy Disc 4. Bokeh by Diffraction 5. 1/3” lens Response (Example) 6. What does In/Out of Focus mean? 7. Depth of Field 8. How to use Bokeh to shoot impressive pictures. 9. Note for AF100 shooting 3. Crop Factor 1. How to use Crop Factor 2. Foal Length and Depth of Field by Imager Size 3. What is the benefit of large sensor? 4. Appendix 1. Size of Imagers 2. Color Separation Filter 3. Sensitivity Comparison 4. ASA Sensitivity 5. Depth of Field Comparison by Imager Size 6. F Stop to get the same Depth of Field 7. Back Focus and Flange Back (Flange Focal Distance) 8. Distance Error by Flange Back Error 9. View Angle Formula 10. Conceptual Schema – Relationship between Iris and Resolution 11. What’s the difference between Video Camera Lens and Still Camera Lens 12. Depth of Field Formula 1.What changes when you use the different imager size camera? 1. Focal Length changes 58mm + + It becomes 35mm Full Frame Standard Lens (CANON, NIKON, LEICA etc.) AG-AF100 28mm Wide Lens 2. Iris (F Stop) changes *distance to object：2m Depth of Field changes *Iris：F4 2m 0m F4 F2 X X <35mm Still Camera> 0.26m 0.2m 0.4m 0.26m 0.2m F4 <4/3 inch> X 0.9m X F2 0.6m 0.4m 0.26m 0.2m Depth of Field 3.
  • The Plumbers Telescope-English

    The Plumbers Telescope-English

    240.BLT KLAUS HÜNIG than 10mm. Use sandpaper to smooth the hole and then roughen the inside of the plug The Plumber’s Telescope to provide a good base for the glue. Remove Kit for an astronomical refracting telescope with Put a small amount of glue evenly all dust and loose plastic bits. 30x magnification, fromusing any 40mm local drain DIY pipes store around the inner side of the end with the Step 8: tags, again without drops or strings. Apply a generous amount of glue onto the Push the eyepiece into the holder from disk holding the eyepiece and fit it into the the tag side and slide it into place by socket plug so that the hole in the disk sits pushing it onto the work surface so it is centrally over the hole in the plug. Again flush with the six tags. take care that no glue gets onto the surface of the lens. After the glue has set, push the plug into the second push-fit coupling. This •Achromatic objective lens, finishes the construction of the eyepiece Ø 40mm, f +450mm holder. •Colour corrected Plössl eyepiece, 15mm, f +15mm Step 5: D. The final assembly Ø Open the 11mm central hole in Part C Step 9: •Tripod adapter (without tripod) Remove the rubber seal from the open end of (blind) using a sharp knife and then •Indestructible HT tubing Shopping list for the DIY store: remove the part from the cardboard. the eyepiece holder. Then fit the eyepiece Fold the six tags backwards and glue the holder on the open end of the objective lens •Shows Moon craters, phases tube.
  • James Short and John Harrison: Personal Genius and Public Knowledge

    James Short and John Harrison: Personal Genius and Public Knowledge

    Science Museum Group Journal James Short and John Harrison: personal genius and public knowledge Journal ISSN number: 2054-5770 This article was written by Jim Bennett 10-09-2014 Cite as 10.15180; 140209 Research James Short and John Harrison: personal genius and public knowledge Published in Autumn 2014, Issue 02 Article DOI: http://dx.doi.org/10.15180/140209 Abstract The instrument maker James Short, whose output was exclusively reflecting telescopes, was a sustained and consistent supporter of the clock and watch maker John Harrison. Short’s specialism placed his work in a tradition that derived from Newton’s Opticks, where the natural philosopher or mathematician might engage in the mechanical process of making mirrors, and a number of prominent astronomers followed this example in the eighteenth century. However, it proved difficult, if not impossible, to capture and communicate in words the manual skills they had acquired. Harrison’s biography has similarities with Short’s but, although he was well received and encouraged in London, unlike Short his mechanical practice did not place him at the centre of the astronomers’ agenda. Harrison became a small part of the growing public interest in experimental demonstration and display, and his timekeepers became objects of exhibition and resort. Lacking formal training, he himself came to be seen as a naive or intuitive mechanic, possessed of an individual and natural ‘genius’ for his work – an idea likely to be favoured by Short and his circle, and appropriate to Short’s intellectual roots in Edinburgh. The problem of capturing and communicating Harrison’s skill became acute once he was a serious candidate for a longitude award and was the burden of the specially appointed ‘Commissioners for the Discovery of Mr Harrison’s Watch’, whose members included Short.
  • Back Matter (PDF)

    Back Matter (PDF)

    [ 395 ] INDEX TO THE PHILOSOPHICAL TRANSACTIONS, S e r ie s A, V o l . 193. A. Abney (W. de W.). The Colour Sensations in Terms of Luminosity, 259. Atmospheric electricity—experiments in connection with precipitation (Wilson), 289. Bakebian Lectube. See Ewing and Kosenhain. C. Colour-blind, neutral points in spectra found by (Abney), 259. Colour sensations in terms of luminosity (Abney), 259. Condensation nuclei, positively and negatively charged ions as (W ilson), 289. Crystalline aggregates, plasticity in (Ewing and Rosenhain), 353. D. Dawson (H. M.). See Smithells, Dawson, and Wilson VOL. CXCIII.— Ao : S F 396 INDEX. Electric spark, constitution of (Schuster and Hemsalech), 189; potential—variation with pressure (Strutt), 377. Electrical conductivity of flames containing vaporised salts (Smithells, Dawson, and Wilson), 89. Electrocapillary phenomena, relation to potential differences between‘solutions (Smith), 47. Electrometer, capillary, theory of (Smith), 47. Ewing (J. A.) and Rosenhain (W.). The Crystalline Structure of Metals.—Bakerian Lecture, 353. F. Filon (L. N. G ). On the Resistance to Torsion of certain Forms of Shafting, with special Reference to the Effect of Keyways, 309. Flames, electrical conductivity of, and luminosity of salt vapours in (Smithells, Dawson, and Wilson), 89. G. Gravity balance, quartz thread (Threlfall and Pollock), 215. H. Hemsalech (Gustav). See Schuster and Hemsalech. Hertzian oscillator, vibrations in field of (Pearson and Lee), 159. Hysteresis in the relation of extension to stress exhibited by overstrained iron (Muir), 1. I. Ions, diffusion into gases, determination of coefficient (Townsend), 129. Ions positively and negatively charged, as condensation nuclei (Wilson), 289. Iron, recovery of, from overstrain (Muir), 1.
  • Longitudinal Chromatic Aberration

    Longitudinal Chromatic Aberration

    Longitudinal Chromatic Aberration Red focus Blue focus LCA Transverse Chromatic Aberration Decentered pupil Transverse Chromatic Aberration Chromatic Difference of Refraction Atchison and Smith, JOSA A, 2005 Why is LCA not really a problem? Chromatic Aberration Halos (LCA) Fringes (TCA) www.starizona.com digitaldailydose.wordpress.com Red-Green Duochrome test • If the letters on the red side stand out more, add minus power; if the letters on the green side stand out more, add plus power. • Neutrality is reached when the letters on both backgrounds appear equally distinct. Colligon-Bradley P. J Ophthalmic Nurs Technol. 1992 11(5):220-2. Transverse Chromatic Aberration Lab #7 April 15th Look at a red and blue target through a 1 mm pinhole. Move the pinhole from one edge of the pupil to the other. What happens to the red and blue images? Chromatic Difference of Magnification Chief ray Aperture stop Off axis source Abbe Number • Also known as – Refractive efficiency – nu-value –V-value –constringence Refractive efficiencies for common materials water 55.6 alcohol 60.6 ophthalmic crown glass 58.6 polycarbonate 30.0 dense flint glass 36.6 Highlite glass 31.0 BK7 64.9 Example • Given the following indices of refraction for BK7 glass (nD = 1.519; nF = 1.522; nC = 1.514) what is the refractive efficiency? • What is the chromatic aberration of a 20D thin lens made of BK7 glass? Problem • Design a 10.00 D achromatic doublet using ophthalmic crown glass and dense flint glass Carl Friedrich Gauss 1777-1855 Heinrich Seidel 1842-1906 Approximations to