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Contrast transfer function
About: Contrast transfer function is a research topic. Over the lifetime, 934 publications have been published within this topic receiving 26533 citations.
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TL;DR: In this paper, the authors describe the aberration fields for a combination of plane symmetric systems, including spherical aberration, coma, astigmatism, defocus, and distortion.
Abstract: By generalizing the wave aberration function to include plane symmetric systems, we describe the aberration fields for a combination of plane symmetric systems. The combined system aberration coefficients for the fields of spherical aberration, coma, astigmatism, defocus and distortion depend on the individual aberration coefficients and the orientations of the individual plane symmetric component systems. The aberration coefficients can be used to calculate the locations of the field nodes for the different types of aberration, including coma, astigmatism, defocus and distortion. This work provides an alternate view for combining aberrations in optical systems.
16 citations
TL;DR: It is shown both theoretically and experimentally that two-photon fluorescence imaging experiences less spherical aberration and can thus propagate to a deeper depth within a thick medium.
Abstract: We compare the effects of spherical aberration on the penetration depth of single-photon and two-photon excitation for instances in which the aberration is caused by the refractive-index mismatch when a beam is focused through an interface. It is shown both theoretically and experimentally that two-photon fluorescence imaging experiences less spherical aberration and can thus propagate to a deeper depth within a thick medium.
16 citations
TL;DR: In this paper, a liquid crystal (LC) lens was designed and fabricated to compensate the spherical aberration caused by a difference in substrate thickness, and the curvature control with a spherical LC lens was optimized to maintain the aberration of a Blu-ray optical pickup even for a thickness variation of ± 25 µm.
Abstract: In multilayer recording, it is strongly required to compensate the spherical aberration caused by a difference in substrate thickness. A novel liquid crystal (LC) lens is designed and fabricated to compensate the spherical aberration in this study. The new structure of the LC lens includes both concave and convex surfaces, which can compensate the spherical aberration with a relatively long range. Since a previously developed LC panel showed a very low tolerance to the shift of an objective lens, a new component has been proposed with a special LC lens structure to improve both the tolerance and compensation range. By optimized curvature control with a spherical LC lens, the aberration of a Blu-ray optical pickup can be maintained at 0.018λrms even for a thickness variation of ±25 µm. Finally, the LC lens has been fabricated using a standard one drop filling (ODF) process and evaluated by measuring the variation in focal length as a function of applied voltage.
16 citations
16 citations
TL;DR: The contrast-transfer-function approximation, widely used in various phase-contrast imaging techniques, is revisited and partially coherent free-space propagators, describing amplitude and phase in-line contrast, are introduced and their properties are investigated.
Abstract: The contrast-transfer-function (CTF) approximation, widely used in various phase-contrast imaging techniques, is revisited. CTF validity conditions are extended to a wide class of strongly absorbing and refracting objects, as well as to nonuniform partially coherent incident illumination. Partially coherent free-space propagators, describing amplitude and phase in-line contrast, are introduced and their properties are investigated. The present results are relevant to the design of imaging experiments with partially coherent sources, as well as to the analysis and interpretation of the corresponding images.
16 citations