Topic
Angular aperture
About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.
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TL;DR: The position of the most focused point of a diffracted Gaussian beam through a finite aperture lens is investigated experimentally and numerically and the effect of the curvature of the equiphase surface of the incident beam on the diffraction field is discussed.
Abstract: The position of the most focused point of a diffracted Gaussian beam through a finite aperture lens is investigated experimentally and numerically. It depends on the definition of the point, but it will be of most practical interest to define the point as the position where the maximum energy is received by a finite aperture detector. In considering the problem, we also discuss the effect of the curvature of the equiphase surface of the incident beam on the diffraction field.
29 citations
TL;DR: In this article, the amplitude curves of the interior and aperture fields as functions of position for a variety of cavity and aperture sizes were obtained and the results exhibited in the form of amplitude curves.
Abstract: A plane wave is symmetrically incident on a spherical shell with a circular aperture. The fields inside and outside the cavity are expanded in terms of spherical vector wave functions and the modal coefficients are found by application of the least squares method to the boundary conditions. Computed data are obtained and the results exhibited in the form of amplitude curves of the interior and aperture fields as functions of position for a variety of cavity and aperture sizes. Within the cavity it appears that the field variations are primarily determined by the cavity size and that the aperture size serves only to scale them.
28 citations
TL;DR: In this paper, the authors examined the transmission characteristics of spherical plate electrostatic analyzers, for external particle sources, as functions of angular coordinates α and β, and particle energy E. They showed that G is of the order of unity.
Abstract: We examine the transmission characteristics of spherical plate electrostatic analyzers, for external particle sources, as functions of angular coordinates α and β, and particle energy E. The angle α is in the plane of the particle's trajectory; β is in the plane containing the point of incidence and perpendicular to the radius vector from the center of electrostatic force. We express the total energy‐geometrical factor F, which is the ratio of transmitted particle flux (particles/sec) to directional intensity (particles/cm2·sec·sr·keV), in the functional form F≡GαβEAβ0ΔαΔE, where βo, and Δα are angular parameters and ΔE the energy resolution, all appropriately defined. We give methods for determining the function G and present some specific examples. We show that G is of the order of unity. A surprising result is that βo, which is a measure of the angular aperture in β space, may differ appreciably from the value expected intuitively on the basis of the angular dimensions of analyzer plates. The angles α ...
28 citations
Patent•
15 Jun 1993TL;DR: In this paper, a light source for radiating coherent light onto an object to be detected on a surface of which a circuit pattern is formed, a focusing device for focusing the light emitted from the light source onto the object, a device for moving the incident light focused at the predetermined angular aperture relative to the object to detect, and a detector for receiving scattered light produced upon incidence of the focused light onto the target, and which detects foreign matter on the target on the basis of an output signal from the detector.
Abstract: A foreign particle detecting apparatus comprises a light source for radiating coherent light onto an object to be detected on a surface of which a circuit pattern is formed, a focusing device for focusing the light emitted from the light source onto the object to be detected at a predetermined angular aperture, a device for moving the incident light focused at the predetermined angular aperture relative to the object to be detected, and a detector for receiving scattered light produced upon incidence of the focused light onto the object to be detected, and which detects foreign matter on the object to be detected on the basis of an output signal from the detector. Foreign matter is discriminated from the circuit pattern on the basis of the output signal from the detector means. The detector comprises at least two light-receiving elements, separated by a spatial angle substantially equal to or slightly larger than the angular aperture of the incident light, for individually outputting signals.
28 citations
TL;DR: Improvements in the quality of reconstructions from synthetic aperture intensity measurements are demonstrated experimentally and by computer simulations.
Abstract: The resolution of the reconstructed wave by a phase-retrieval method using a volume-speckle field depends on the aperture defined by the size of the CCD array. The use of a larger aperture is introduced by measuring the speckle field at two different positions in the transverse plane and stitching the measurements together. Improvements in the quality of reconstructions are demonstrated experimentally and by computer simulations. Undesirable effects of camera tilt on the quality of reconstructions from synthetic aperture intensity measurements are experimentally observed and corrected.
28 citations