טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBenny Yael
SubjectStudy of the Optics of the Human Eye
DepartmentDepartment of Physics
Supervisor Dr. Erez Ribak
Full Thesis textFull thesis text - English Version


Abstract

The human eye suffers from monochromatic aberrations which originate from its structure as well as from chromatic aberrations which stem from its dispersion. Optical aberrations in the human eye impose a major physical limit on spatial vision. Therefore, correction of these aberrations could allow a generation of high-resolution ophthalmoscopes on one hand and a better vision on the other hand . In this study we investigated the ocular aberrations .


The first part of this study addresses the monochromatic aberrations. The human eye wais modelled by software and a corrector design based on optimization process was suggested. The principle of the corrector is to decrease the effect of aberrations of the anterior cornea by immersing it in saline solution. A system based on Hartmann-Shack detection was built to examine aberrations of eyes in-vivo with and without the suggested corrector . Software based on the Fast-Fourier-Transform algorithm, was developed as an alternative to the commonly used Centroid method, for reconstructing the aberrated ocular wave front phases from the measured gradients.


The second part of this work deals with the longitudinal chromatic aberration. The longitudinal aberration of the human eye is about 2.1 Diopters in the visible spectrum (400 - 700 nm), and about 0.4 Diopters for the near infra-red (700 - 900 nm) . A chromatic corrector was designed for a modelled eye, based on optimization results. The optimization process was performed to get a minimum longitudinal aberration without introducing monochromatic aberrations, and by keeping a wide field of view. Comparison with former achromatizing lenses shows better off-axis results, i.e. less effect of transverse chromatic aberration on going farther into peripheral fields. Measurements were taken to examine the corrector optical quality and effect on vision. The results show a good correction of the longitudinal aberration for all subjects tested. The visual acuity with and without the corrector was tested. Two tested subjects gave different results, but in both cases the differences in visual acuity, with and without the corrector were minor. Despite the good correction of longitudinal chromatic aberration which was obtained, no significant improvement in visual acuity was observed. Those results are similar to results of former studies .


We propose to use this corrector, which provides a very good correction in the visible range and in the near IR as well, for improving ophthalmic view of the fundus .