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Dynamic Range Compression/Expansion of Light Beams by Photorefractive CrystalsApparatus is provided which greatly reduced the intensity of bright portions of an image while only moderately reducing the brightness of dimmer portions of the image, to thereby compress the range of light intensities to facilitate detection of the image. The apparatus includes a light detector device formed by a chip of photorefractive material. A two-dimensional array of light beams from an object to be detected, passes through a beam splitter to form two arrays of light beams. The two arrays of light beams are directed at different angles against a surface of the chip of photorefractive material, the two arrays of light beams forming coincident images on the surface. One of the the two-dimensional arrays of beams emerging from an opposite surface of the chip has a lower range of intensities, to facilitate detection of the object despite very bright spots on its image. The other array of light beams emerging from the chip has a greater range of intensities than the unprocessed image of the object.
Document ID
19890004706
Acquisition Source
Headquarters
Document Type
Other - Patent
External Source(s)
NPO-17140-1-CU
Authors
Li-Jen Cheng
(Colorado State University Fort Collins, United States)
Hua-Kuang Liu
(Jet Propulsion Laboratory La Cañada Flintridge, United States)
Date Acquired
August 14, 2013
Publication Date
September 20, 1988
Publication Information
Publisher: United States Patent and Trademark Office
Subject Category
Optics
Accession Number
89N14077
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-PATENT-4,772,785
Patent Application
US-PATENT-APPL-SN-125021
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