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Spatial filter

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


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors use the theory of periodic structures, full-wave electromagnetic, and microwave circuit simulations to explain the resonant modes that propagate in metallic grids having rectangular unit cells constructed over a ground plane.
Abstract: We use the theory of periodic structures, full-wave electromagnetic, and microwave circuit simulations to explain the resonant modes that propagate in metallic grids having rectangular unit cells constructed over a ground plane. We show that these metallic grids can support two types of resonant modes that have rectangular and hyperbolic isofrequency dispersion contours. By exploiting the spatial dispersion properties of these modes, a microwave 3GHz∕6GHz harmonic splitter and a highly selective 5.8GHz∕6.2GHz diplexer are designed and simulated. Furthermore, we provide experimental results for the diplexer and for the harmonic splitter, synthesized in microstrip technology. The proposed metallic grids utilize continuous unloaded transmission-line segments thus leading to spatial-filtering devices that are easy to fabricate and are scalable to terahertz frequencies and beyond.

29 citations

Patent
27 Dec 1982
TL;DR: In this article, a pattern recognition and optical image processing system employing dynamically alterable magneto-optic display assemblies operating as light modulators is described, where a first pattern is digitized and used to drive a first magneto optic display assembly disposed in a light beam.
Abstract: A pattern recognition and optical image processing system employing dynamically alterable magneto-optic display assemblies operating as light modulators. A first pattern is digitized and used to drive a first magneto-optic display assembly disposed in a light beam. The pattern impressed upon the light beam is sensed at the Fourier plane and digitized as a representation of the spatial filter pattern of the first pattern. A second pattern is digitized. The digitized second pattern and the digitized spatial filter pattern of the first pattern are used to drive a pair of magneto-optic display assemblies disposed in a single light beam. The resultant correlation pattern is sensed and the degree of correlation match between the Fourier transform of one pattern and the spatial filter pattern of the other pattern is used as indication of the probability of a pattern match between the first and second patterns.

29 citations

Patent
09 Sep 1996
TL;DR: In this paper, it was shown that the photoinduced anisotropy of photochromic materials such as bacteriorhodopsin, organic fulgides, azo and fluorescent dyes, phycobiliproteins, rhodopsins, and their analogs, is dependent on the intensity of a polarized actinic beam that illuminates the material and the intensity profile of one or more input beams.
Abstract: The invention relates to systems and methods for optical Fourier processing and logic operations based on the discovery that the photoinduced anisotropy of photochromic materials such as bacteriorhodopsin, organic fulgides, azo and fluorescent dyes, phycobiliproteins, rhodopsins, and their analogs, is dependent on the intensity of a polarized actinic beam that illuminates the material and the intensity profile of one or more input beams. This intensity dependence can be used to implement a simple, real-time, self-adaptive optical processing, i.e., spatial filtering, system for Fourier processing of optical input images. This optical processing system can be used to process a wide variety of optical input images, from projected still images to live motion picture images.

29 citations

Journal ArticleDOI
TL;DR: The theory underlying the image formation process for imaging correlography is reviewed, emphasizing the spatial filtering effects that sparse collecting apertures have on the reconstructed imagery, and image recovery with sparse arrays of intensity detectors is demonstrated.
Abstract: Imaging correlography is a technique for constructing high resolution images of laser-illuminated objects from measurements of back-scattered (nonimaged) laser speckle intensity patterns In this paper, we investigate the possibility of implementing an imaging correlography system with sparse arrays of intensity detectors The theory underlying the image formation process for imaging correlography is reviewed, emphasizing the spatial filtering effects that sparse collecting apertures have on the reconstructed imagery We then demonstrate image recovery with sparse arrays of intensity detectors through the use of computer experiments in which laser speckle measurements are digitally simulated It is shown that the quality of imagery reconstructed using this technique is visibly enhanced when appropriate filtering techniques are applied The signal-to-noise ratio of the process and its dependency on array redundancy and number of speckle pattern measurements is also discussed

29 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202265
202181
2020144
2019180
2018179