Topic
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 article, an expression for the longitudinal spherical aberration produced by a spherical refracting surface from parallel incident light in the fifth-order approximation is derived, and a simple experiment to measure the location of focal points formed by nonparaxial rays is also described.
Abstract: An expression for the longitudinal spherical aberration produced by a spherical refracting surface from parallel incident light in the fifth‐order approximation is derived. A simple experiment to measure the location of focal points formed by nonparaxial rays is also described. The results of the measurements are in good agreement with the theory.
3 citations
TL;DR: In this paper, the performance of microscope objectives used with near infrared light has been examined by scanning a grating across the focused image of a point source in order to find the conditions for maximum correction of spherical aberration.
Abstract: The performance of microscope objectives used with near infrared light has been examined by scanning a grating across the focused image of a point source. Objectives have been assessed under different conditions by varying wavelength, tube-length and coverslip thickness corrections in order to find the conditions for maximum correction of spherical aberration. Computations of light intensity around the focus have been convolved with an amplitude grating so that the amount of spherical aberration could be estimated. Results showed that significant reductions in the amount of spherical aberration could be achieved by altering the tube length.
3 citations
TL;DR: In this article, the propagation and imaging of polarized light through optical systems described by a polarization aberration expansion is treated by combining a scalar operator calculus with the Jones calculus. And the martrix-operator framework provides a means for handling diffraction and propagation in optical systems containing polarization aberrations.
Abstract: The propagation and imaging of polarized light through optical systems described by a polarization aberration expansion is treated by combining a scalar operator calculus with the Jones calculus. The martrix-operator framework provides a means for handling diffraction and propagation in optical systems containing polarization aberrations. An expansion for the polarization aberration function of an optical system, similar to the expansion of the wavefront aberration function into defocus, tilt, piston, and higher-order terms, is analysed. These polarization aberration terms introduce phase changes in the diffraction image proportional to the first and second derivatives of the non-polarization aberrated image structure.
3 citations
TL;DR: In this paper, the black-white contrast of small dislocation loops in elastically anisotropic crystals is calculated using the first-order perturbation solution for the dynamical two-beam diffraction condition.
Abstract: The black-white contrast of small dislocation loops in elastically anisotropic crystals is calculated using the first-order perturbation solution for the dynamical two-beam diffraction condition. It is shown that under realistic conditions the contrast is given essentially by the projection of the displacement field of the dislocation loop onto the image plane. From the Fourier representation [gtilde](k) of the Green's function of the displacement field of point forces the projected displacement field of the loop is obtained by two-dimensional inversion of the Fourier transformation. The final result is applicable for arbitrary directions of the incident electron beam and implies as the critical step the determination of the six roots of the denominator of [gtilde](k) in the image plane. Examples referring to crystals of cubic symmetry demonstrate that the orientation and shape of the black-white contrast figure becomes more and more insensitive to the actual directions of the loop normal n and t...
3 citations
TL;DR: Frozen-hydrated microtubules have been studied by cryoelectron microscopy and their relationship with the computed or X ray diffraction patterns, and the influence of the contrast transfer function are described.
Abstract: Frozen-hydrated microtubules have been studied by cryoelectron microscopy We have described some structural features of microtubules, their relationship with the computed or X ray diffraction patterns, and the influence of the contrast transfer function
3 citations