DOCSLIB.ORG

Visual Effect of the Combined Correction of Spherical and Longitudinal Chromatic Aberrations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Visual Effect of the Combined Correction of Spherical and Longitudinal Chromatic Aberrations Visual effect of the combined correction of spherical and longitudinal chromatic aberrations Pablo Artal 1,* , Silvestre Manzanera 1, Patricia Piers 2 and Henk Weeber 2 1Laboratorio de Optica, Centro de Investigación en Optica y Nanofísica (CiOyN), Universidad de Murcia, Campus de Espinardo, 30071 Murcia, Spain 2AMO Groningen, Groningen, The Netherlands *[email protected] Abstract: An instrument permitting visual testing in white light following the correction of spherical aberration (SA) and longitudinal chromatic aberration (LCA) was used to explore the visual effect of the combined correction of SA and LCA in future new intraocular lenses (IOLs). The LCA of the eye was corrected using a diffractive element and SA was controlled by an adaptive optics instrument. A visual channel in the system allows for the measurement of visual acuity (VA) and contrast sensitivity (CS) at 6 c/deg in three subjects, for the four different conditions resulting from the combination of the presence or absence of LCA and SA. In the cases where SA is present, the average SA value found in pseudophakic patients is induced. Improvements in VA were found when SA alone or combined with LCA were corrected. For CS, only the combined correction of SA and LCA provided a significant improvement over the uncorrected case. The visual improvement provided by the correction of SA was higher than that from correcting LCA, while the combined correction of LCA and SA provided the best visual performance. This suggests that an aspheric achromatic IOL may provide some visual benefit when compared to standard IOLs. ©2010 Optical Society of America OCIS codes: (330.0330) Vision, color, and visual optics; (330.4460) Ophthalmic optics and devices; (330.5510) Psycophysics; (220.1080) Active or adaptive optics. References and Links 1. J. Porter, A. Guirao, I. G. Cox, and D. R. Williams, “Monochromatic aberrations of the human eye in a large population,” J. Opt. Soc. Am. A 18 (8), 1793–1803 (2001). 2. J. F. Castejón-Mochón, N. López-Gil, A. Benito, and P. Artal, “Ocular wave-front aberration statistics in a normal young population,” Vision Res. 42 (13), 1611–1617 (2002). 3. P. Artal, E. Berrio, A. Guirao, and P. Piers, “Contribution of the cornea and internal surfaces to the change of ocular aberrations with age,” J. Opt. Soc. Am. A 19 (1), 137–143 (2002). 4. J. Tabernero, P. Piers, A. Benito, M. Redondo, and P. Artal, “Predicting the optical performance of eyes implanted with IOLs to correct spherical aberration,” Invest. Ophthalmol. Vis. Sci. 47 (10), 4651–4658 (2006). 5. T. Oshika, S. D. Klyce, R. A. Applegate, and H. C. Howland, “Changes in corneal wavefront aberrations with aging,” Invest. Ophthalmol. Vis. Sci. 40 (7), 1351–1355 (1999). 6. A. Guirao, M. Redondo, and P. Artal, “Optical aberrations of the human cornea as a function of age,” J. Opt. Soc. Am. A 17 (10), 1697–1702 (2000). 7. A. Guirao, M. Redondo, E. Geraghty, P. Piers, S. Norrby, and P. Artal, “Corneal optical aberrations and retinal image quality in patients in whom monofocal intraocular lenses were implanted,” Arch. Ophthalmol. 120 (9), 1143–1151 (2002). 8. J. T. Holladay, P. A. Piers, G. Koranyi, M. van der Mooren, and N. E. S. Norrby, “A new intraocular lens design to reduce spherical aberration of pseudophakic eyes,” J. Refract. Surg. 18 (6), 683–691 (2002). 9. P. Artal, “History of IOLs that correct spherical aberration,” J. Cataract Refract. Surg. 35 (6), 962–963, author reply 963–964 (2009). 10. U. Mester, P. Dillinger, and N. Anterist, “Impact of a modified optic design on visual function: clinical comparative study,” J. Cataract Refract. Surg. 29 (4), 652–660 (2003). 11. R. M. Kershner, “Retinal image contrast and functional visual performance with aspheric, silicone, and acrylic intraocular lenses. Prospective evaluation,” J. Cataract Refract. Surg. 29 (9), 1684–1694 (2003). 12. M. Packer, I. H. Fine, R. S. Hoffman, and P. A. Piers, “Prospective randomized trial of an anterior surface modified prolate intraocular lens,” J. Refract. Surg. 18 (6), 692–696 (2002). #118780 - $15.00 USD Received 19 Oct 2009; revised 11 Jan 2010; accepted 11 Jan 2010; published 13 Jan 2010 (C) 2010 OSA 18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 1637 13. H. Zhao, and M. A. Mainster, “The effect of chromatic dispersion on pseudophakic optical performance,” Br. J. Ophthalmol. 91 (9), 1225–1229 (2007). 14. P. A. Piers, E. J. Fernandez, S. Manzanera, S. Norrby, and P. Artal, “Adaptive optics simulation of intraocular lenses with modified spherical aberration,” Invest. Ophthalmol. Vis. Sci. 45 (12), 4601–4610 (2004). 15. E. J. Fernández, S. Manzanera, P. Piers, and P. Artal, “Adaptive optics visual simulator,” J. Refract. Surg. 18 (5), S634–S638 (2002). 16. G. Wald, and D. R. Griffin, “The change in refractive power of the human eye in dim and bright light,” J. Opt. Soc. Am. 37 (5), 321–336 (1947). 17. R. E. Bedford, and G. Wyszecki, “Axial chromatic aberration of the human eye,” J. Opt. Soc. Am. 47 (6), 564– 565 (1957). 18. W. N. Charman, and J. A. M. Jennings, “Objective measurements of the longitudinal chromatic aberration of the human eye,” Vision Res. 16 (9), 999–1005 (1976). 19. P. A. Howarth, and A. Bradley, “The longitudinal chromatic aberration of the human eye, and its correction,” Vision Res. 26 (2), 361–366 (1986). 20. E. J. Fernández, A. Unterhuber, B. Povazay, B. Hermann, P. Artal, and W. Drexler, “Chromatic aberration correction of the human eye for retinal imaging in the near infrared,” Opt. Express 14 (13), 6213–6225 (2006). 21. M. Rynders, B. Lidkea, W. Chisholm, and L. N. Thibos, “Statistical distribution of foveal transverse chromatic aberration, pupil centration, and angle-psi in a population of young-adult eyes,” J. Opt. Soc. Am. A 12 (10), 2348–2357 (1995). 22. S. Marcos, S. A. Burns, P. M. Prieto, R. Navarro, and B. Baraibar, “Investigating sources of variability of monochromatic and transverse chromatic aberrations across eyes,” Vision Res. 41 (28), 3861–3871 (2001). 23. F. W. Campbell, and R. W. Gubisch, “Effect of chromatic aberration on visual acuity,” Journal of Physiology- London 192 , 345 (1967). 24. J. S. McLellan, S. Marcos, P. M. Prieto, and S. A. Burns, “Imperfect optics may be the eye’s defence against chromatic blur,” Nature 417 (6885), 174–176 (2002). 25. S. Ravikumar, L. N. Thibos, and A. Bradley, “Calculation of retinal image quality for polychromatic light,” J. Opt. Soc. Am. A 25 (10), 2395–2407 (2008). 26. G. Y. Yoon, and D. R. Williams, “Visual performance after correcting the monochromatic and chromatic aberrations of the eye,” J. Opt. Soc. Am. A 19 (2), 266–275 (2002). 27. A. C. S. Van Heel, “Correcting the spherical and chromatic aberrations of the eye,” J. Opt. Soc. Am. 36 , 237–239 (1946). 28. A. L. Lewis, M. Katz, and C. Oehrlein, “A modified achromatizing lens,” Am. J. Optom. Physiol. Opt. 59 (11), 909–911 (1982). 29. I. Powell, “Lenses for correcting chromatic aberration of the eye,” Appl. Opt. 20 (24), 4152–4155 (1981). 30. J. A. Diaz, M. Irlbauer, and J. A. Martinez, “Diffractive-refractive hybrid doublet to achromatize the human eye,” J. Mod. Opt. 51 (14), 2223–2234 (2000). 31. Y. Benny, S. Manzanera, P. M. Prieto, E. N. Ribak, and P. Artal, “Wide-angle chromatic aberration corrector for the human eye,” J. Opt. Soc. Am. A 24 (6), 1538–1544 (2007). 32. D. A. Atchison, M. Ye, A. Bradley, M. J. Collins, X. X. Zhang, H. A. Rahman, and L. N. Thibos, “Chromatic aberration and optical power of a diffractive bifocal contact lens,” Optom. Vis. Sci. 69 (10), 797–804 (1992). 33. P. Piers, and H. Weeber, “Ophthalmic lens,” US Patent 6,830,332, Dec. 14, 2004. 34. A. Bradley, “Glenn A. Fry Award Lecture 1991: perceptual manifestations of imperfect optics in the human eye: attempts to correct for ocular chromatic aberration,” Optom. Vis. Sci. 69 (7), 515–521 (1992). 35. C. Lapicque, “La formation des Images retiniennes,” (Ed. de la Revue d'Optique, Paris, 1937). 36. P. A. Piers, S. Manzanera, P. M. Prieto, N. Gorceix, and P. Artal, “Use of adaptive optics to determine the optimal ocular spherical aberration,” J. Cataract Refract. Surg. 33 (10), 1721–1726 (2007). 37. P. M. Prieto, F. Vargas-Martin, S. Goelz, and P. Artal, “Analysis of the performance of the Hartmann-Shack sensor in the human eye,” J. Opt. Soc. Am. A 17 (8), 1388–1398 (2000). 38. D. A. Buralli, G. M. Morris, and J. R. Rogers, “Optical performance of holographic kinoforms,” Appl. Opt. 28 (5), 976–983 (1989). 39. S. Manzanera, C. Canovas, P. M. Prieto, and P. Artal, “A wavelength tunable wavefront sensor for the human eye,” Opt. Express 16 (11), 7748–7755 (2008). 40. L. N. Thibos, M. Ye, X. X. Zhang, and A. Bradley, “The chromatic eye. A new reduced eye model of ocular chromatic aberration in humans,” Appl. Opt. 31 (19), 3594–3600 (1992). 41. A. B. Watson, and D. G. Pelli, “QUEST: a Bayesian adaptive psychometric method,” Percept. Psychophys. 33 (2), 113–120 (1983). 42. Y. K. Nio, N. M. Jansonius, V. Fidler, E. Geraghty, S. Norrby, and A. C. Kooijman, “Age-related changes of defocus-specific contrast sensitivity in healthy subjects,” Ophthalmic Physiol. Opt. 20 (4), 323–334 (2000). 43. P. Artal, L. Chen, E. J. Fernández, B. Singer, S. Manzanera, and D. R. Williams, “Neural compensation for the eye’s optical aberrations,” J. Vis. 4(4), 281–287 (2004). 44. X. X. Zhang, A. Bradley, and L. N. Thibos, “Achromatizing the human eye: the problem of chromatic parallax,” J. Opt. Soc. Am. A 8(4), 686–691 (1991). 45. M. Baumeister, J.
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]
  • Spherical Aberration ¥ Field Angle Effects (Off-Axis Aberrations) Ð Field Curvature Ð Coma Ð Astigmatism Ð Distortion
    Astronomy 80 B: Light Lecture 9: curved mirrors, lenses, aberrations 29 April 2003 Jerry Nelson Sensitive Countries LLNL field trip 2003 April 29 80B-Light 2 Topics for Today • Optical illusion • Reflections from curved mirrors – Convex mirrors – anamorphic systems – Concave mirrors • Refraction from curved surfaces – Entering and exiting curved surfaces – Converging lenses – Diverging lenses • Aberrations 2003 April 29 80B-Light 3 2003 April 29 80B-Light 4 2003 April 29 80B-Light 8 2003 April 29 80B-Light 9 Images from convex mirror 2003 April 29 80B-Light 10 2003 April 29 80B-Light 11 Reflection from sphere • Escher drawing of images from convex sphere 2003 April 29 80B-Light 12 • Anamorphic mirror and image 2003 April 29 80B-Light 13 • Anamorphic mirror (conical) 2003 April 29 80B-Light 14 • The artist Hans Holbein made anamorphic paintings 2003 April 29 80B-Light 15 Ray rules for concave mirrors 2003 April 29 80B-Light 16 Image from concave mirror 2003 April 29 80B-Light 17 Reflections get complex 2003 April 29 80B-Light 18 Mirror eyes in a plankton 2003 April 29 80B-Light 19 Constructing images with rays and mirrors • Paraxial rays are used – These rays may only yield approximate results – The focal point for a spherical mirror is half way to the center of the sphere. – Rule 1: All rays incident parallel to the axis are reflected so that they appear to be coming from the focal point F. – Rule 2: All rays that (when extended) pass through C (the center of the sphere) are reflected back on themselves.
    [Show full text]
  • Topic 3: Operation of Simple Lens
    V N I E R U S E I T H Y Modern Optics T O H F G E R D I N B U Topic 3: Operation of Simple Lens Aim: Covers imaging of simple lens using Fresnel Diffraction, resolu- tion limits and basics of aberrations theory. Contents: 1. Phase and Pupil Functions of a lens 2. Image of Axial Point 3. Example of Round Lens 4. Diffraction limit of lens 5. Defocus 6. The Strehl Limit 7. Other Aberrations PTIC D O S G IE R L O P U P P A D E S C P I A S Properties of a Lens -1- Autumn Term R Y TM H ENT of P V N I E R U S E I T H Y Modern Optics T O H F G E R D I N B U Ray Model Simple Ray Optics gives f Image Object u v Imaging properties of 1 1 1 + = u v f The focal length is given by 1 1 1 = (n − 1) + f R1 R2 For Infinite object Phase Shift Ray Optics gives Delta Fn f Lens introduces a path length difference, or PHASE SHIFT. PTIC D O S G IE R L O P U P P A D E S C P I A S Properties of a Lens -2- Autumn Term R Y TM H ENT of P V N I E R U S E I T H Y Modern Optics T O H F G E R D I N B U Phase Function of a Lens δ1 δ2 h R2 R1 n P0 P ∆ 1 With NO lens, Phase Shift between , P0 ! P1 is 2p F = kD where k = l with lens in place, at distance h from optical, F = k0d1 + d2 +n(D − d1 − d2)1 Air Glass @ A which can be arranged to|giv{ze } | {z } F = knD − k(n − 1)(d1 + d2) where d1 and d2 depend on h, the ray height.
    [Show full text]
  • An Instrument for Measuring Longitudinal Spherical Aberration of Lenses
    U. S. Department of Commerce Research Paper RP20l5 National Bureau of Standards Volume 42, August 1949 Part of the Journal of Research of the National Bureau of Standards An Instrument for Measuring Longitudinal Spherical Aberration of Lenses By Francis E. Washer An instrument is described that permits the rapid determination of longitudinal spheri­ cal and longitudinal chromatic aberration of lenses. Specially constructed diaphragms isolate successive zones of a lens, and a movable reticle connected to a sensitive dial gage enables the operator to locate the successive focal planes for the different zones. Results of measurement are presented for several types of lenses. The instrument can also be used without modification to measure the mall refractive powers of goggle lenses. 1. Introduction The arrangement of these elements is shown diagrammatically in figui' e 1. To simplify the In the comse of a research project sponsored by description, the optical sy tem will be considered the Army Air Forces, an instrument was developed in three parts, each of which forms a definite to facilitate the inspection of len es used in the member of the whole system. The axis, A, is construction of reflector sights. This instrument common to the entire system; the axis is bent at enabled the inspection method to be based upon the mirror, lvI, to conserve space and simplify a rapid determination of the axial longitudinal operation by a single observer. spherical aberration of the lens. This measme­ Objective lens L j , mirror M, and viewing screen, ment was performed with the aid of a cries of S form the first part.
    [Show full text]
  • Spherical Aberration
    Spherical Aberration Lens Design OPTI 517 Prof. Jose Sasian Spherical aberration • 1) Wavefront shapes 8) Merte surface • 2) Fourth and sixth 9) Afocal doublet order coefficients 10) Aspheric plate • 3) Using an aspheric 11) Meniscus lens surface 12) Spaced doublet • 3) Lens splitting 13) Aplanatic points • 4) Lens bending 14) Fourth-order • 5) Index of refraction dependence dependence 16) Gaussian to flat top • 6) Critical air space • 7) Field lens Prof. Jose Sasian Review of key conceptual figures Prof. Jose Sasian Conceptual models F P N P’ N’ F’ First-order optics model provides a useful reference and provides graphical method to trace first-order rays Entrance and exit pupils provide a useful reference to describe the input and E E’ output optical fields Prof. Jose Sasian Object, image and pupil planes Prof. Jose Sasian Rays and waves geometry Geometrical ray model and wave model for light propagation. Both Ray Are consistent and are y 'I H different representations W/n of the same phenomena. Aperture Normal vector line Image plane Optical axis Reference sphere Wavefront Exit pupil plane Prof. Jose Sasian Spherical aberration Prof. Jose Sasian Spherical aberration is uniform over the field of view 2 W040 Wavefront Spots Prof. Jose Sasian Ray caustic Prof. Jose Sasian Two waves of spherical aberration through focus. From positive four waves to negative seven waves, at one wave steps of defocus. The first image in the middle row is at the Gaussian image plane. Prof. Jose Sasian Cases of zero spherical aberration from a spherical surface 2 1 2 u W040 WS040 I SI A y 8 n y 0 A 0 0 /un ' un un / /' y=0 the aperture is zero or the surface is at an image A=0 the surface is concentric with the Gaussian image point on axis u’/n’-u/n=0 the conjugates are at the aplanatic points Aplanatic means free from error; freedom from spherical aberration and coma Prof.
    [Show full text]
  • Optical Performance Factors
    1ch_FundamentalOptics_Final_a.qxd 6/15/2009 2:28 PM Page 1.11 Fundamental Optics www.cvimellesgriot.com Fundamental Optics Performance Factors After paraxial formulas have been used to select values for component focal length(s) and diameter(s), the final step is to select actual lenses. As in any engineering problem, this selection process involves a number of tradeoffs, wavelength l including performance, cost, weight, and environmental factors. The performance of real optical systems is limited by several factors, material 1 including lens aberrations and light diffraction. The magnitude of these index n 1 effects can be calculated with relative ease. Gaussian Beam Optics v Numerous other factors, such as lens manufacturing tolerances and 1 component alignment, impact the performance of an optical system. Although these are not considered explicitly in the following discussion, it should be kept in mind that if calculations indicate that a lens system only just meets the desired performance criteria, in practice it may fall short material 2 v2 of this performance as a result of other factors. In critical applications, index n 2 it is generally better to select a lens whose calculated performance is significantly better than needed. DIFFRACTION Figure 1.14 Refraction of light at a dielectric boundary Diffraction, a natural property of light arising from its wave nature, poses a fundamental limitation on any optical system. Diffraction is always Optical Specifications present, although its effects may be masked if the system has significant aberrations. When an optical system is essentially free from aberrations, its performance is limited solely by diffraction, and it is referred to as diffraction limited.
    [Show full text]
  • Wide Field Telescope Using Spherical Mirrors
    Wide field telescope using spherical mirrors J. H. Burge and J. R. P. Angel Optical Sciences Center and Steward Observatory University of Arizona, Tucson, AZ 85721 ABSTRACT A new class of optical telescope is required to obtain high resolution spectra of many faint, dis- tant galaxies. These dim objects require apertures approaching 30 meters in addition to many hours of integration per object, and simultaneous observation of as many galaxies as possible. Several astronomical telescopes of 20, 30, 50, even 100 meters are being proposed for general purpose astronomy. We present a different concept here with a 30-m telescope optimized for wide field, multi-object spectroscopy. The optical design uses a fully steerable, quasi- Cassegrain telescope in which the primary and secondary mirrors are parts of concentric spheres, imaging a 3° field of view onto a spherical surface. The spherical aberration from the mirrors is large (about 2 arc minutes) but it is constant across the field. Our system design uses numerous correctors, placed at the Cassegrain focus, each of which corrects over a small field of a few arc seconds. These can be used for integral field spectroscopy or for direct imaging us- ing adaptive optics. Hundreds of these units could be placed on the focal surface during the day to allow all-night exposures of the desired regions. We believe that this design offers an economical system that can be dedicated for several important types of astronomical observa- tion. Keywords : telescope, optical design, astronomical optics 1. INTRODUCTION The optical design of the Schmidt telescope is well known to provide excellent images over a large field of view by using a spherical primary mirror and a corrector located at the stop of the telescope at the center of curvature of the primary mirror.
    [Show full text]
  • Spherical Aberration Correction in a Scanning Transmission Electron Microscope Using a Sculpted Foil
    Spherical aberration correction in a scanning transmission electron microscope using a sculpted foil Roy Shiloh1*†, Roei Remez1†, Peng-Han Lu2†, Lei Jin2, Yossi Lereah1, Amir H. Tavabi2, Rafal E. Dunin- Borkowski2, and Ady Arie1 1School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel. 2Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, Jülich, Germany. *Correspondence to: [email protected] †These authors contributed equally to this work. Nearly twenty years ago, following a sixty year struggle, scientists succeeded in correcting the bane of electron lenses, spherical aberration, using electromagnetic aberration correction. However, such correctors necessitate re-engineering of the electron column, additional space, a power supply, water cooling, and other requirements. Here, we show how modern nanofabrication techniques can be used to surpass the resolution of an uncorrected scanning transmission electron microscope more simply by sculpting a foil of material into a refractive corrector that negates spherical aberration. This corrector can be fabricated at low cost using a simple process and installed on existing electron microscopes without changing their hardware, thereby providing an immediate upgrade to spatial resolution. Using our corrector, we reveal features of Si and Cu samples that cannot be resolved in the uncorrected microscope. Electron microscopy has been revolutionised by the introduction of aberration correction, which has allowed a vast range of new scientific questions to be addressed at the atomic scale. Although the first electron microscope was built 85 years ago [1], its rotationally-symmetric, static, charge-free lenses are fundamentally incapable of correcting the dominant spherical aberration [2].
    [Show full text]
  • The Fundamentals of Spherical Aberration Fifteen Pearls Every Cataract Surgeon Should Know
    Today’s PRACTICE CATARACT FUNDAMENTALS The Fundamentals of Spherical Aberration Fifteen pearls every cataract surgeon should know. BY GEORGE H.H. BEIKO, BM, BCH, FRCSC Pearl No. 1: The wavefront characteristics of light can be described in mathematical terms using different systems, including Zernike polynomials and Fourier analysis. Using Zernike polynomials, sphere (defocus) and cylinder (astigmatism) describe the two higher-order aberrations (HOAs) that we measure with phoropters. These aberrations account for approximately 83% of the magnitude of the wavefront of light. Spherical aberration and coma are the next most significant HOAs. Spherical aberration describes the amount of bending that occurs as light passes through a refracting surface, such as the cornea, and compares the relative position of the focal points for the peripheral and central light beams. Positive spherical aberration occurs when the peripheral Figure 1. Wavefront data derived from corneal topography, rays are focused in front of the central rays; this value is using Easygraph (Oculus). expressed in microns. Pearl No. 2: The wavefront of the human eye can be eye, the anterior corneal surface accounts for 98% of wavefront measured using wavefront analyzers such as Shack- changes. Small-incision (less than 2.8 mm) cataract surgery Hartmann systems and Tracey aberrometers (iTRACE; causes minimal changes in the spherical aberration of the eye Tracey Technologies, Corp.). Corneal topographers can and, for practical terms, can be considered to have no effect.2 measure the front surface of the cornea (Figure 1), and Pearl No. 4: Measurements of spherical aberrations this data can be transformed to determine the HOAs of of the anterior corneal surface have found the average the cornea.
    [Show full text]
  • Coma Aberration
    Coma aberration Lens Design OPTI 517 Prof. Jose Sasian Coma 0.25 wave 1.0 wave 2.0 waves 4.0 waves Spot diagram 2 2 W H, , W200 H W020 W111H cos 4 3 2 2 2 W040 W131H cos W222 H cos 2 2 3 4 W220 H W311H cos W400 H ... Prof. Jose Sasian Coma though focus Prof. Jose Sasian Cases of zero coma 1 u WAAy131 2 n •At y=0, surface is at an image •A=0, On axis beam concentric with center of curvature •A-bar=0, Off-axis beam concentric, chief ray goes through the center of curvature •Aplanatic points Prof. Jose Sasian Cases of zero coma Prof. Jose Sasian Aplanatic-concentric Prof. Jose Sasian Coma as a variation of magnification with aperture I 1 u WH131 , AAyH 2 n Prof. Jose Sasian Coma as a variation of magnification with aperture II S S’ m=s’/s Prof. Jose Sasian Sine condition Coma aberration can be considered as a variation of magnification with respect to the aperture. If the paraxial magnification is equal to the real ray marginal magnification, then an optical system would be free of coma. Spherical aberration can be considered as a variation of the focal length with the aperture. u sinU U U’ u' sinU ' Prof. Jose Sasian Sine condition On-axis L Sine condition YY’ L' O’ h YY’ O’ UU’L' L O h’ PP’ PP’ Optical path length between y and y’ is Optical path length between O and O’ is Laxis and does not depend on Y or Y’ Loff-axis = Laxis + L’ - L L = L + h’ n’ sin(U’) - h n sin(U) Lhsin( U ) L ''sin(') hU off-axis axis u sinU hn' 'sin( U ') hn sin( U ) u' sinU ' That is: OPD has no linear phase errors as a function Prof.of field Jose of Sasian view! Imaging a grating m sin(U ) d d sin(U ) m d'sin(U ') Prof.
    [Show full text]
  • Chapter 8 Aberrations Chapter 8
    Chapter 8 Aberrations Chapter 8 Aberrations In the analysis presented previously, the mathematical models were developed assuming perfect lenses, i.e. the lenses were clear and free of any defects which modify the propagating optical wavefront. However, it is interesting to investigate the effects that departures from such ideal cases have upon the resolution and image quality of a scanning imaging system. These departures are commonly referred to as aberrations [23]. The effects of aberrations in optical imaging systems is a immense subject and has generated interest in many scientific fields, the majority of which is beyond the scope of this thesis. Hence, only the common forms of aberrations evident in optical storage systems will be discussed. Two classes of aberrations are defined, monochromatic aberrations - where the illumination is of a single wavelength, and chromatic aberrations - where the illumination consists of many different wavelengths. In the current analysis only an understanding of monochromatic aberrations and their effects is required [4], since a source of illumination of a single wavelength is generally employed in optical storage systems. The following chapter illustrates how aberrations can be modelled as a modification of the aperture pupil function of a lens. The mathematical and computational procedure presented in the previous chapters may then be used to determine the effects that aberrations have upon the readout signal in optical storage systems. Since the analysis is primarily concerned with the understanding of aberrations and their effects in optical storage systems, only the response of the Type 1 reflectance and Type 1 differential detector MO scanning microscopes will be investigated.
    [Show full text]
  • Measurement of Monochromatic Ocular Aberrations of Human Eyes As a Function of Accommodation by the Howland Aberroscope Technique DAVID A
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Vision Res. Vol. 35, No. 3, pp. 313 323, 1995 ~ Pergamon Copyright © 1995 Elsevier Science Ltd 0042-6989(94)00139-1 Printed in Great Britain. All rights reserved 0042-6989/95 $7.00 + 0.00 Measurement of Monochromatic Ocular Aberrations of Human Eyes as a Function of Accommodation by the Howland Aberroscope Technique DAVID A. ATCHISON,* MICHAEL J. COLLINS,* CHRISTINE F. WILDSOET,* JAMES CHRISTENSEN,* MICHAEL D. WATERWORTHt Received 24 November 1995. in revised form 14 April 1994 Further development of the objective version of the Howland and Howland [(1976) Science, 193, 580-582; (1977) Journal of the Optical Society of America, 67, 1508-1518] aberroscope technique for measuring ocular aberrations is described. Compensation for refractive corrections and calibration is discussed. The technique was used to investigate the effect of accommodation upon the mono- chromatic aberrations of the right eyes of 15 subjects. Coma and coma-like aberrations were the dominant aberrations for most people at different accommodation levels, thus confirming previous findings. Variations in aberrations were considerable between subjects. About half the subjects showed the classical trend towards negative spherical aberration with accommodation. Changes in spherical aberration with accommodation in this study were less than that found in previous studies where all monochromatic aberration was considered to be spherical aberration. Aberration
    [Show full text]