Spatial filter

About: Spatial filter is a research topic. Over the lifetime, 6170 publications have been published within this topic receiving 100451 citations.

Method and equipment for detecting foreign matter

Abstract: PURPOSE: To extract only foreign matter information without extremely damaging foreign matter scattering light, by illuminating a wafer from an oblique upper part with a rotation angle wherein reflected diffraction light in the directions of x-axis and y-axis does not enter an objective. CONSTITUTION: A wafer 1 is so arranged that two principal pairs of line edge group constituting a circuit pattern 2 on the wafer 1 become parallel to x-axis and y-axis, respectively. When the wafer is illuminated from an oblique upper part at rotation angles of 45° with respect to x-axis and y-axis, the reflected diffraction light from the line edge group parallel to x-axis and y-axis does not enter an objective 7, so that pattern information is eliminated. The line edge group among the pattern 2 with angles of 45° with repect to x-axis and y-axis becomes vertical to laser beam, so that the reflected diffraction light constitutes a Fourier transform image on a Fourier transform plane 11. By arranging a spatial filter 10 on the transform plane 11, the pattern information is eliminated. Thereby extracting foreign matter information only. COPYRIGHT: (C)1989,JPO&Japio

Color display device with intervening lens and spatial filter or with overlapping beams of chromatically separated light between the chromatic separator and lens array

Abstract: A color display device comprises a source of light simultaneously emitting several ranges of chromatic components and a spatial light modulator comprising several dots, each dot comprising at least one sub-pixel per range of chromatic component to be displayed. Between the light source and the spatial light modulator there are provided at least one chromatic separator angularly separating the light of the different chromatic range along different directions, a lens focusing the light of the different chromatic ranges at distinct points or along distinct lines contained in a determined plane, at least one spatial filter located along this determined plane and selectively filtering the light of the different chromatic ranges, and an array of lenses, each enabling the focusing of the light of each chromatic range substantially on a sub-pixel.

Laser three-dimensional imaging device based on single-photon detector

Abstract: The invention discloses a laser three-dimensional imaging device based on a single-photon detector, belonging to the technical field of photoelectric instruments. A target to be detected is irradiated by the laser pulse emitted by a pulsed laser via a scanning system; the returning photons are received by a receiving/emitting co-axial optical system, i.e., the returning photons are received by a double-gating single-photon detecting module via a spectral filter and a spatial filter and an arriving pulse is outputted, so that the photon flight time of the target measuring point can be measured by combining the laser emission detection and the multi-photon arriving pulse time; and a data processing unit is used for carrying out the coordinate conversion based on the position and attitude data, scanning mirror targeting data, and photon flight time of the three-dimensional imaging device, de-noising and three-dimensional image construction and correction, so as to output the reliable target three-dimensional range image. The invention solves the problems that the existing laser three-dimensional imaging device is incapable of penetrating vegetation and camouflage and being miniaturized when conducting long-distance operations.

A method and an apparatus for generating a phase-modulated wave front of electromagnetic radiation

Abstract: The present invention provides a method and a system for generating a phase-modulated wave front. According to the present invention, the spatial phase-modulation is not performed on the different parts of the wave front individually as in known POSLMs. Rather, the spatial phase-modulation of the present invention is performed by generating an amplitude modulation in the wave front, Fourier or Fresnel transforming the amplitude modulated wave front, filtering Fourier or Fresnel components of the Fourier or Fresnel distribution with a spatial filter such as a phase contrast filter, and regenerating the wave front whereby the initial amplitude modulation has transformed into a phase-modulation.