DOCSLIB.ORG

Magnesiumrich Intralensar Structures In

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Magnesiumrich Intralensar Structures In [Palaeontology, Vol. 50, Part 5, 2007, pp. 1031–1037] MAGNESIUM-RICH INTRALENSAR STRUCTURES IN SCHIZOCHROAL TRILOBITE EYES by MARTIN R. LEE, CLARE TORNEY and ALAN W. OWEN Department of Geographical and Earth Sciences, University of Glasgow, Gregory Building, Lilybank Gardens, Glasgow G12 8QQ, UK; e-mail: [email protected] Typescript received 14 March 2007; accepted in revised form 25 May 2007 Abstract: The interpretation of the lenses of schizochroal ucts reflect original differences in mineral chemistry between trilobite eyes as aplanatic doublets by Clarkson and Levi-Setti the upper lens unit and lower intralensar bowl. The turbidity over 30 years ago has been widely accepted. However, the of the bowl and of the core within the upper part of the lens means of achieving a difference in refractive index across the are the result of their greater microporosity and abundance interface between the two parts of each lens to overcome of microdolomite inclusions, both of which were products of spherical aberration has remained a matter of speculation diagenetic replacement of original magnesian calcite in these and lately it has been argued that the doublet structure itself areas. Such a difference in magnesium concentration in the is no more than a diagenetic artefact. Recent advances in original calcite has long been postulated as one of the ways technologies for imaging, chemical analysis and crystallo- by which the interface between these lens units could have graphic characterization of minerals at high spatial resolu- produced an aberration-free image and the present study tions have enabled a re-examination of the structure of provides the first direct evidence of such a chemical contrast, calcite lenses at an unprecedented level of detail. The lenses thus confirming the doublet hypothesis. in the eyes of the specimen of Dalmanites sp. used in the ori- ginal formulation of the aplanatic doublet hypothesis are Key words: trilobite, schizochroal eyes, magnesian calcite, shown to have undergone diagenetic alteration, but its prod- microdolomite. The schizochroal eyes of the Lower Ordovician–Upper matter of speculation and, most recently, the doublet Devonian phacopine trilobites are unique amongst the structure itself has been interpreted as a diagenetic artefact Arthropoda (Horva´th et al. 1997). They are characterized (Bruton and Haas 2003). by a relatively small number of highly biconvex calcite Clarkson and Levi-Setti (1975, p. 665) speculated that lenses separated by cuticular material, the interlensar sclera the intralensar bowl was composed of calcite containing (see Clarkson et al. 2006 for review). The internal structure organic material, possibly chitin, whereas the upper unit of these lenses and the mechanism by which they focused was pure calcite. Horva´th (1989) argued that the lower light have been the subject of considerable debate. Drawing lens unit was wholly organic in composition whereas on their own observations and those of others (e.g. Towe Campbell (1975) and Miller and Clarkson (1980) sugges- 1973), Clarkson and Levi-Setti (1975) argued that each ted that differences in magnesium concentrations between lens was a doublet with the curved junction between the the two parts of the doublet might have provided the upper lens unit and the underlying bowl acting as a cor- necessary contrast in refractive index but they lacked the recting surface with a change in refractive index across it evidence to support this interpretation using the tech- bringing light into sharp focus. This elegant explanation niques then available. Nonetheless, such a difference in drew analogies between the upper lens units and the apla- magnesium content has been assumed to be the case (e.g. natic lenses for correcting spherical aberration postulated Fortey and Chatterton 2003). Magnesium enrichment has by the Renaissance scientists Descartes and Huygens (see also been invoked for an enigmatic structure termed the also Levi-Setti 1993). The doublet structure, seen in several core, reported in the upper lens units in some schizo- species in both transmitted light (e.g. Campbell 1975; Mil- chroal eyes (see Clarkson et al. 2006). ler and Clarkson 1980) and in etched surfaces by scanning More fundamentally, Bruton and Haas (2003) disputed electron microscopy (SEM) (Miller and Clarkson 1980), the doublet model and argued that the intralensar struc- and Clarkson and Levi-Setti’s explanation for it have tures described by Clarkson and Levi-Setti were diagenetic become widely accepted. However, the means of achieving artefacts. They proposed that focusing of light by lenses the necessary difference in refractive index across the inter- of the Devonian phacopine Geesops sparsinodosus was face of the two components of each lens has remained a achieved by grading the refractive index of lens calcite by ª The Palaeontological Association doi: 10.1111/j.1475-4983.2007.00710.x 1031 1032 PALAEONTOLOGY, VOLUME 50 an increase in organic material in the lateral parts of each quality map whereby contrast represents differences in the lens, thereby overcoming spherical aberration. quality of electron backscatter (Kikuchi) patterns which Recent technological advances in imaging and chemical reflect variations in crystallographic orientation of the and crystallographic analysis at high spatial resolutions calcite and the presence of subgrain boundaries and have enabled the structure of calcite lenses to be elucida- pores; the latter give very poor patterns. The precise ted at an unprecedented level of detail. The various hypo- orientation of the pole to a specified crystal plane for theses for lens structure and function outlined above can each point in the EBSD maps can also be plotted as a now be tested and here we report results of a re-examina- pole figure. Quantitative chemical analyses were acquired tion of the lenses of the specimen of an un-named species using a Cameca SX50 electron probe operated at of Dalmanites (horizon and locality not known) that 15 kV ⁄ 10 nA and with a 10-lm defocused spot. Stan- formed a crucial part of the doublet hypothesis of Clark- dardization used wollastonite (Ca), periclase (Mg), Mn son and Levi-Setti (1975; also Horva´th 1989; Levi-Setti metal (Mn) and Fe metal (Fe). Count times were typically 1993). If the lenses were doublets, the two parts of each 30 s on peak and 10 s on background, and detection lens must have differed significantly in refractive index limits were 0Æ06 weight per cent MnCO3 and 0Æ07 weight and therefore in composition. The new technologies for per cent FeCO3. mineral characterization now provide an opportunity to assess whether such compositional differences did origin- ally exist at the described interface. The absence of a con- RESULTS trast between the upper lens unit and bowl sufficient to yield the necessary difference in refractive index (e.g. cal- The trilobite exoskeleton studied is contained in a skeletal cite vs. chitin, magnesium-poor calcite vs. magnesium- packstone together with articulated and disarticulated rich calcite) would lend support to the contention by microfossils, including ostracodes, and fragments of trilo- Bruton and Haas that the doublet structure is a diagenetic bites and echinoderms. Small angular grains of quartz artefact, or at the very least that all of the original differ- also occur. The limestone is orange in optical-CL and has ences within the structure have been completely overprin- a greater luminescence intensity than the trilobite cuticles. ted by recrystallization during burial. In plane polarized transmitted light the lenses are defined clearly and have abrupt boundaries with the interlensar sclera and limestone (Text-fig. 1). Many of the lenses METHODS contain a bowl and core, both of which are turbid and pseudopleochroic in plane polarized transmitted light and The internal structure of the lenses and adjacent exoskel- so are distinguished clearly from the enclosing optically eton on polished thin sections of the indeterminate spe- clear lens calcite (Text-fig. 1). A small proportion of the cies of Dalmanites was observed initially by transmitted lenses are turbid throughout, although the bowl can still light and optical cathodoluminescence (optical-CL) micro- be recognized by a greater opacity. BSE imaging shows scopy. Higher resolution imaging and chemical and crys- that the turbidity of the bowl and core is due mainly to tallographic analysis of the lenses used an FEI Quanta 200F field-emission environmental scanning electron microscope equipped with an EDAX ⁄ TSL X-ray micro- analysis and electron backscatter diffraction (EBSD) sys- tem. Conventional backscattered electron (BSE) imaging of lenses in thin section was used in conjunction with a new technique of charge contrast (CC) microscopy that utilizes secondary electrons emitted from uncoated samples with the microscope operated in environmental mode. Contrast within CC images reflects variations in the accumulation and dissipation of electrons on the sample surface (Watt et al. 2000) and may be comparable with that formed by optical-CL, but the CC images can be acquired at much higher magnifications and from non-luminescent minerals (Cuthbert and Buckman 2005). EBSD was used to determine the crystallographic orien- TEXT-FIG. 1. Plane polarized transmitted light image of a tation of lens calcite, and sample preparation and instru- single lens. Faint trabeculae that fan out downwards can be ment operating conditions are described in Dalbeck et al. identified within the core. The subhorizontal black line at the (2006). Here the EBSD data are presented as an image top of the lens is a fracture. LEE ET AL.: INTRALENSAR STRUCTURES IN SCHIZOCHROAL TRILOBITE EYES 1033 abundant micropores (Text-fig. 2A). The core has a in central and outer parts of the lenses, but fan outwards microporosity of c. 1Æ2 vol. per cent (determined from towards the base of the lens where they are orientated at computer analysis of BSE images) and the pores range in angles of up to 40 degrees to the c-axis (Text-fig. 3A).
Load more

Recommended publications
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • Engineering an Achromatic Bessel Beam Using a Phase-Only Spatial Light Modulator and an Iterative Fourier Transformation Algorithm
    Optics Communications 383 (2017) 64–68 Contents lists available at ScienceDirect Optics Communications journal homepage: www.elsevier.com/locate/optcom Engineering an achromatic Bessel beam using a phase-only spatial light modulator and an iterative Fourier transformation algorithm Marie Walde a, Aurélie Jost a, Kai Wicker a,b,c, Rainer Heintzmann a,c,n a Institut für Physikalische Chemie (IPC), Abbe Center of Photonics, Friedrich-Schiller-Universität, Jena, Germany b Carl Zeiss AG, Corporate Research and Technology, Jena, Germany c Leibniz Institute of Photonic Technology (IPHT), Jena, Germany article info abstract Article history: Bessel illumination is an established method in optical imaging and manipulation to achieve an extended Received 12 June 2016 depth of field without compromising the lateral resolution. When broadband or multicolour imaging is Received in revised form required, wavelength-dependent changes in the radial profile of the Bessel illumination can complicate 13 August 2016 further image processing and analysis. Accepted 21 August 2016 We present a solution for engineering a multicolour Bessel beam that is easy to implement and Available online 2 September 2016 promises to be particularly useful for broadband imaging applications. A phase-only spatial light mod- Keywords: ulator (SLM) in the image plane and an iterative Fourier Transformation algorithm (IFTA) are used to Bessel beam create an annular light distribution in the back focal plane of a lens. The 2D Fourier transformation of Spatial light modulator such a light ring yields a Bessel beam with a constant radial profile for different wavelength. Non-diffracting beams & 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND Iterative Fourier transform algorithm Frequency filtering license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
    [Show full text]
  • Lens/Mirrors
    Refractive Optical Design Systems Any lens system is a tradeoff of many factors Add optical elements (lens/mirrors) to balance these Many different types of lens systems used Want to look at each from the following Performance Requirements Resolution of the lens – how good at seeing fine details Also compensation to reduce lens aberrations Field of View: How much of a object is seen in the image from the lens system F# - that is how fast is the lens i.e. how good is the lens at low light exposures Packaging requirements- can you make it rugged & portable Spectral Range – what wavelengths do you want to see Also how to prevent chromatic aberrations Single Element Poor image quality with spherical lens Creates significant aberrations especially for small f# Aspheric lens better but much more expensive (2-3x higher $) Very small field of view High Chromatic Aberrations – only use for a high f# Need to add additional optical element to get better images However fine for some applications eg Laser with single line Where just want a spot, not a full field of view Landscape Lens Single lens but with aperture stop added i.e restriction on lens separate from the lens Lens is “bent” around the stop Reduces angle of incidence – thus off axis aberrations Aperture either in front or back Simplest cameras use this Achromatic Doublet Typically brings red and blue into same focus Green usually slightly defocused Chromatic blur 25x less than singlet (for f#=5 lens) Cemented achromatic doublet poor at low f# Slight improvement
    [Show full text]
  • Combinations of Achromatic Doublets
    Combinations of achromatic doublets Introduction to aberrations OPTI 518 Prof. Jose Sasian Copyright © 2019 Plano convex lens N-BK7 : Petzval radius -151.7 mm 1 CPetzval IV Petzval n Prof. Jose Sasian Copyright © 2019 Wollaston meniscus lens WW222/0.8 220P • Artificially flattening the field • Periscopic lenses Prof. Jose Sasian Copyright © 2019 Periskop lens • Principle of symmetry • No distortion Prof. Jose Sasian Copyright © 2019 Field curvature • Old achromat • New achromat N-BK7 : Petzval radius -151.7 mm N-BK7 and N-F2: Petzval radius -139.99 mm (+139.99 for negative doublet) N-BAK1 and N-LLF6: Petzval radius -185 mm 1 12 vv 12 CPetzval IV Petzval nn12 vvnn 1212 Prof. Jose Sasian Copyright © 2019 Chevalier landscape lens WW222/0.8 220P • F/5 telescope doublet used in reverse and with an aperture stop in front Prof. Jose Sasian Copyright © 2019 Rapid rectilinear • F/8 • Glass selection is key to minimize spherical aberration while artificially flattening the field RMS spot size Prof. Jose Sasian Copyright © 2019 Lister microscope objective • Telecentric y 1 B 2 IA IB 0 22 22 IIA IIB II Ayy A IIA B B IIB y2 B IIA2 IIB III11yy B B IIB 0 1 yB *2 SSIII III2 SSSS II I Prof. Jose Sasian Copyright © 2019 Lister microscope objective Practical solution • RMS spot size in waves • Two identical doublets • Spherical aberration and coma are corrected • Astigmatism is small • Telecentric • Less vignetting Prof. Jose Sasian Copyright © 2019 Aplanatic concentric meniscus lens • Optical speed is increased by an N factor Prof. Jose Sasian Copyright © 2019 Petzval portrait objective f’=144 mm; F/3.7; FOV=+/- 16.5⁰.
    [Show full text]
  • Lens Aberrations Fundamentals
    11/05/2021 Lens Aberrations Fundamentals Optical Engineering Prof. Elias N. Glytsis School of Electrical & Computer Engineering National Technical University of Athens Imaging Conjugate Points Imaging Limitations • Scattering • Aberrations • Diffraction F. L. Pedrotti and L. S. Pedrotti, Introduction to Optics, 2nd Ed., Prentice Hall, 1993. Prof. Elias N. Glytsis, School of ECE, NTUA 2 Aberrations (3rd order – Seidel) Chromatic Monochromatic Unclear Deformation Image of Image • Spherical • Coma • Astigmatism rd 3 order • Field Curvature • Distortion rd 3 order optics.hanyang.ac.kr/~shsong/20-Aberration%20theory.pdf Prof. Elias N. Glytsis, School of ECE, NTUA 3 Spherical Aberration Paraxial Approximation: Fermat’s Principle: Prof. Elias N. Glytsis, School of ECE, NTUA 4 Spherical Aberration (continue) Fermat’s Principle: Prof. Elias N. Glytsis, School of ECE, NTUA 5 Spherical Aberration (continue) Using Trigonometry and Snell’s Law: Triangle OAI: Prof. Elias N. Glytsis, School of ECE, NTUA 6 Spherical Aberration (3rd order – Seidel) 3rd order – Seidel Prof. Elias N. Glytsis, School of ECE, NTUA 7 Spherical Aberration (3rd order – Seidel) Prof. Elias N. Glytsis, School of ECE, NTUA 8 Spherical Aberration (3rd order – Seidel) Prof. Elias N. Glytsis, School of ECE, NTUA 9 Spherical Aberration (3rd order – Seidel) 3-order Approximation: Prof. Elias N. Glytsis, School of ECE, NTUA 10 Spherical Aberration (3rd order – Seidel) 3-order Approximation (without any more approximations-exact): Prof. Elias N. Glytsis, School of ECE, NTUA 11 Spherical Aberration - Example Prof. Elias N. Glytsis, School of ECE, NTUA 12 Aberrations (3rd order – Seidel) F. L. Pedrotti et al., “Introduction to Optics”, 3nd Ed., Prentice Hall, New Jersey,2006 Prof.
    [Show full text]
  • Design and Correction of Optical Systems
    Design and Correction of optical Systems Part 12: Correction of aberrations 1 Summer term 2012 Herbert Gross 2 Overview 1. Basics 2012-04-18 2. Materials 2012-04-25 3. Components 2012-05-02 4. Paraxial optics 2012-05-09 5. Properties of optical systems 2012-05-16 6. Photometry 2012-05-23 7. Geometrical aberrations 2012-05-30 8. Wave optical aberrations 2012-06-06 9. Fourier optical image formation 2012-06-13 10. Performance criteria 1 2012-06-20 11. Performance criteria 2 2012-06-27 12. Correction of aberrations 1 2012-07-04 13. Correction of aberrations 2 2012-07-11 14. Optical system classification 2012-07-18 3 Contents 12.1 Symmetry principle 12.2 Lens bending 12.3 Correcting spherical aberration 12.4 Coma, stop position 12.5 Astigmatism 12.6 Field flattening 12.7 Chromatical correction 12.8 Higher order aberrations 4 Principle of Symmetry . Perfect symmetrical system: magnification m = -1 . Stop in centre of symmetry . Symmetrical contributions of wave aberrations are doubled (spherical) . Asymmetrical contributions of wave aberration vanishes W(-x) = -W(x) . Easy correction of: coma, distortion, chromatical change of magnification front part rear part 2 3 1 5 Symmetrical Systems Ideal symmetrical systems: . Vanishing coma, distortion, lateral color aberration . Remaining residual aberrations: 1. spherical aberration 2. astigmatism 3. field curvature 4. axial chromatical aberration 5. skew spherical aberration 6 Symmetry Principle . Application of symmetry principle: photographic lenses . Especially field dominant aberrations can be corrected . Also approximate fulfillment of symmetry condition helps significantly: quasi symmetry . Realization of quasi- symmetric setups in nearly all photographic systems Ref : H.
    [Show full text]
  • New Light on the Invention of the Achromatic Telescope Objective”
    Remarks to the Article: “New Light on the Invention of the Achromatic Telescope Objective” Igor Nesterenko FRIB/NSCL, Michigan State University, East Lansing, MI 48824, USA Budker Institute of Nuclear Physics, Novosibirsk, 630090, RUSSIA (corresponding author, e-mail: [email protected]) Abstract The article analysis was carried out within the confines of the replication project of the telescope, which was used by Mikhail Lomonosov at observation the transit of Venus in 1761. At that time he discovered the Venusian atmosphere. It is known that Lomonosov used Dollond’s 4.5 feet long achromatic telescope. The investigation revealed significant faults in the description of the approximation method, which most likely was used by J. Dollond & Son during manufacturing of the early achromatic lenses. Introduction In the article [1] R. Willach described the research of the four early achromatic lenses. Two doublet lenses were made by Dollond: one is flint-forward type and other lens is crown-forward type. The others two doublet lenses (both flint-forward type) were made by James Ayscough and by Joseph Linnell1. The flint-forward doublets are classified as a first early achromatic lenses in comparison with crown-forward type. The optical parameters of the examined flint-forward doublets are collected in the Table 1. For calculation and comparison of the optical systems, Zemax-EE software was used. Table 1. Optical parameters of the flint-forward achromatic lenses Maker D F R1 R2 tflint Glass tair R3 R4 tcrown Glass Name (mm) (mm) (mm) (mm) (mm) Name (mm) (mm) (mm) (mm) Name Dollond 32.0 773 -1826 190 2.8 E18_F1 0.0 193 -262 3.7 E18_C1 Linnell 24.5 492 -83000 99 1.9 E18_F2 0.3 136 -132 4.0 E18_C2 Ayscough 32.0 790 -803 168 1.1 E18_F3 0.2 220 -171 3.5 E18_C3 The measured refractive indexes of the glasses from the investigated achromatic doublets at the different wavelengths are described in Table 2.
    [Show full text]
  • Chromatic Aberrations
    Chromatic Aberrations Lens Design OPTI 517 Prof. Jose Sasian Second-order chromatic aberrations 22 WH,cos W000 W 200 H WH 111 W 020 • Change of image location with λ (axial or longitudinal chromatic aberration) • Change of magnification with λ (transverse or lateral chromatic aberration Prof. Jose Sasian Chromatic Aberrations • Variation of lens aberrations as a function of wavelength • Chromatic change of focus: W020 • Chromatic change of magnification W111 • Fourth-order:W040 and other • Spherochromatism Prof. Jose Sasian Chromatic Aberrations 2 WH cos W020 111 Prof. Jose Sasian Topics • Chromatic coefficients •Apochromats • Optical glass and selection • Index interpolation • Super-apochromats • Achromats: crown and flint: • Buried surface different solutions • Monochromatic design: one • Achromats: dialyte; single task at a time glass • Mangin lens • Lateral color correction as an • Third-order behavior odd aberration • Spherochromatism • Color correction in the • Secondary spectrum presence of axial color • Tertiary spectrum • Field lens to control lateral color: field lenses in general • Conrady’s D-d sum Prof. Jose Sasian Chromatic aberration coefficients For a system of j surfaces For a system of thin lenses j j Wyy WAnny111 j jj/ 111 i1 i1 i j 1 j 1 2 WAnny / Wy020 020 j jj 2 2 i1 i1 i Prof. Jose Sasian With stop shift W020 0 y WW 2 111y 020 Prof. Jose Sasian Review of paraxial quantities y r u’ s’ n 1 nn/ Prof. Jose Sasian n Chromatic coefficients y2 11 11 Wnn020 ' 2'sr sr y 2 1 1 1 1 W020 n'n' n n 2 s' r s r y 2 1 1 1 1 y n W020 n' n A 2 s' r s r 2 n Prof.
    [Show full text]
  • 502-20 Chromatic Effects
    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.
    [Show full text]