Phase transfer and point-spread function of the human eye determined by a new asymmetric double-pass method.
نویسندگان
چکیده
A recent study has shown that the double-pass method provides a good estimate of the ocular modulation transfer function (MTF) but that it does not yield the phase transfer function (PTF) [J. Opt. Soc. Am. A 12, 195 (1995)]. Therefore, one cannot recover the true retinal point-spread function (PSF). We present a modification of the double-pass method to overcome this problem. The key is to break the symmetry between the two passes. By using an unexpanded Gaussian input beam, we produce a diffraction-limited PSF for the first passes. Then, by using a large exit pupil, we get an aberrated PSF for the second pass. The double-pass aerial image is the cross correlation of both PSF's, so that the Fourier transform of such an aerial image directly provides the true retinal PTF, up to the cutoff frequency of the effective (small), diffraction-limited entrance pupil. The resulting double-pass aerial image is a blurred version of the true retinal PSF. Thus it shows the effect not only of even symmetric aberrations but also of odd and irregular aberrations such as coma. We have explored two different ways to retrieve the true retinal PSF: (a) deblurring of the aerial image and (b) PSF reconstruction combining PTF data with conventional double-pass MTF. We present promising initial results with both artificial and real eyes.
منابع مشابه
Odd aberrations and double-pass measurements of retinal image quality.
We investigated the formation of the aerial image in the double-pass method to measure the optical quality of the human eye. We show theoretically and empirically that the double pass through the eye's optics forces the light distribution in the aerial image to be an even-symmetric function even if the single-pass point-spread function is asymmetric as a result of odd aberrations in the eye. Th...
متن کاملPhase-transfer function of the human eye and its influence on point-spread function and wave aberration.
The bidimensional phase-transfer function (PTF) of the human eye has been computed from aerial retinal images of a point test. These images were previously determined by using a recently developed hybrid optical-digital method. Actual PTF data have been obtained directly without linear variations with spatial frequency and have shown great variations among individual subjects. The influence of ...
متن کاملNew method for fixation point of tibialis posterior tendon transfer
Background: The transfer of the tibialis posterior tendon to the dorsum of foot can restore the function of the paralyzed dorsiflexor muscles of the foot and ankle. In order to reduce the wound complication in the insertion site of tendon to bone by a plantar knop we used a new method of fixation by an absorbable screw inserted dorsally. Methods: we performed this operation on 15 patients in...
متن کاملEvaluation of Models to Describe Temporal Growth in Local Chickens of Ghana
The logistic, Gompertz, Richards and asymmetric logistic growth curve models were fitted to body weight data of local Ghanaian chickens and French SASSO T44 chickens. All four growth models provided good fit for each sex by genotype growth data with R2 values ranging from 86.7% to 96.7%. The rate constant parameter, k, ranged between 0.137 and 0.271 and were significantly different from zero fo...
متن کاملHeat Transfer under Double Turbulent Pulsating Jets Impinging on a Flat Surface
In this study, the numerical analysis of turbulent flow and heat transfer of double pulsating impinging jets on a flat surface has been investigated. The unsteady two-dimensional numerical solution for two similar and dissimilar jets was performed using the RNG k-ε model. The results showed that the RNG k-ε model has more satisfactory predictions of the Nusselt number distribution. Comparisons ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of the Optical Society of America. A, Optics, image science, and vision
دوره 12 11 شماره
صفحات -
تاریخ انتشار 1995