نتایج جستجو برای: aberration
تعداد نتایج: 6840 فیلتر نتایج به سال:
Split laser beams of varying separation were directed through the crystalline lenses of rats of young, old, and intermediate age. The variation in back vertex distance was determined from photographs of the focal effects of each lens. The results indicate that negative spherical aberration of the rat lens increases with age. In addition, local reversals in the slopes of the negative spherical a...
Misalignments always occur in real optical systems. These misalignments do not generate new aberration forms, but they change the aberration field dependence. Two-mirror telescopes have been used in several applications. We analyze a two-mirror telescope configuration that has negligible sensitivity to decenter misalignments. By applying the wave aberration theory for plane-symmetric optical sy...
A technique is described to determine the change in image contrast as a result of the spherical aberration induced by the radial keratotomy procedure. The hypothesis that the loss in contrast sensitivity of the RK eye is due to the change in spherical aberration postsurgically, is found to be acceptable for some patients. However, this is not a sufficient explanation in all cases. This conclusi...
We present a method for manufacturing phase plates to compensate for the wave aberration in the human eye. The wave aberration of the eye is measured in vivo by a new laser ray-tracing method and then compensated for by a phase plate placed in front of the eye. This plate is made from a gray-level single-mask photosculpture in photoresist. Two experiments were carried out, first with an artific...
In this paper, a simulation method for lens design is presented considering the aberration effect. Traditionally, most optical path calculation algorithms are based on aberration theory and result in approximation. For eliminating this problem and avoiding the limitations from aberration theory, this paper considers paraxial rays and others as the same to trace their paths. For checking out the...
PURPOSE To evaluate the quality of vision and depth of focus induced by controlled amounts of negative spherical aberration in patients implanted bilaterally with light-adjustable intraocular lenses. DESIGN Prospective, nonrandomized clinical trial. METHODS Seventeen patients were implanted and treated with appropriate spatial irradiance light profiles. One eye was set for emmetropia, and t...
PURPOSE We investigated the correlations between optical quality parameters obtained from the double-pass system and ocular aberrations obtained from the ray-tracing aberrometer in multifocal intraocular lens (IOL) implanted eyes. MATERIALS AND METHODS Twenty eyes from 20 patients were enrolled in this study. Modulation transfer function cutoff frequency, The Strehl ratio, objective scatter i...
Current ultrasonic scatterer size estimation methods assume that acoustic propagation is free of distortion due to large-scale variations in medium attenuation and sound speed. However, it has been demonstrated that under certain conditions in medical applications, medium inhomogeneities can cause significant field aberrations that lead to B-mode image artifacts. These same aberrations may be r...
PURPOSE To estimate changes in surface shape and gradient refractive index (GRIN) profile in primate lenses as a function of accommodation. To quantify the contribution of surface shape and GRIN to spherical aberration changes with accommodation. METHODS Crystalline lenses from 15 cynomolgus monkeys were studied in vitro under different levels of accommodation produced by a stretching system....
We demonstrate adaptive aberration correction for depth-induced spherical aberration in a multiphoton scanning microscope with a micromachined deformable mirror. Correction was made using a genetic learning algorithm with two-photon fluorescence intensity feedback to determine the desired shape for an adaptive mirror. For a 40x/0.6 NA long working distance objective, the axial scanning range wa...
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