نتایج جستجو برای: aberrations
تعداد نتایج: 17220 فیلتر نتایج به سال:
Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform...
Recently, computer numerically controlled machines have permitted the manufacture of progressive power lenses (PPLs) with different designs. However, the possible differences in optical performance among lens designs are not yet well established. In this work, the spatially resolved aberrations, at 20 relevant locations, of three PPLs with different designs were measured with a Hartmann-Shack w...
Local minima or notches in the defocused contrast sensitivity function (CSF) have been linked to the aberrations of the eye. We use theoretical modeling of the effects of the aberrations to show these notches can be orientation-selective due to the effects of aberration terms such as coma and trefoil. Notches that changed with orientation were observed in the defocused CSF of four subjects. The...
A study of optical aberrations for flat lenses based on phase discontinuities is reported. The wave aberration function and the analytical expression of the aberrations up to the 4th order are derived to describe the performance of both ideal and practical flat lenses. We find that aberration-free focusing is possible under axial illumination but off-axis aberrations appear when the excitation ...
A variable shear lateral shearing interferometer consisting of two holographically produced crossed diffraction gratings is used to test nonrotationally symmetric wavefronts having aberrations greater than 100 wavelengths and slope variations of more than 400 wavelengths/diameter. Comparisons are made with results of Twyman-Green interferometric tests for wavefront aberrations of up to thirty w...
The analytical treatment of linear intracavity phase aberrations and their compensation by an appropriately configured intracavity adaptive optic element is presented in this paper. The approximate geometrical treatment of the effects of intracavity phase aberrations is first treated, followed by a complete exact diffraction integral formulation of the adaptive compensation of linear phase-tilt...
Adaptive optics (AO) is an effective method to compensate the wavefront distortion caused by atmospheric turbulence and system distortion. The accuracy speed of aberration restoration are important factors affecting performance adaptive correction. In recent years, AO correction based on a convolutional neural network (CNN) has been proposed for non-iterative extraction light intensity image fe...
Wave aberrations of isolated ex vivo porcine crystalline lenses were measured by using a point-diffraction interferometer. This method allowed us to gain greater insight into the detailed aberration structure of eye lenses showing systematic presence of some dominant aberrations. In order of significance, astigmatism together with spherical aberration, coma, and trefoil are the main aberrations...
Standard cytochemical methods were used to investigate the ameliorative effect of melatonin (0.2 mM) on chromosomal aberrations in human lymphocyte cultures induced by arsenic (As2O3, 1.4 μM) and/or fluoride (NaF, 34 μM). As2O3 and/or NaF generated a significant increase in the incidence of chromosomal aberrations as compared to control levels. Combined treatment with As2O3 and NaF induced more...
Stimulated emission depletion (STED) microscopes, like all super-resolution methods, are sensitive to aberrations. Of particular importance are aberrations that affect the quality of the depletion focus, which requires a point of near-zero intensity surrounded by strong illumination. We present analysis, modeling, and experimental measurements that show the effects of coma aberrations on deplet...
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