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Title: Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector

Apparatus and method for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO.sub.2 laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart.
Inventors:
 [1]
  1. (Santa Fe, NM)
Issue Date:
OSTI Identifier:
871238
Assignee:
Regents of University of California (Los Alamos, NM) LANL
Patent Number(s):
US 5689335
Contract Number:
W-7405-ENG-36
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM
Country of Publication:
United States
Language:
English
Subject:
apparatus; method; heterodyne-generated; two-dimensional; detector; array; single; element; synthetic-array; heterodyne; detection; permits; single-element; optical; behave; divided; separate; elements; fifteen-element; synthetic; successfully; experimentally; realized; permitting; continuously; parallel; electrical; connection; laser; hgcdte; photodiode; employed; local; oscillator; frequency; incident; spatially; resolvable; regions; surface; mapped; beat; frequencies; determine; photons; prevents; destructive; interference; occurs; multiple; speckles; imaged; similar; spatial; diversity; coherent; lidar; larger; field; view; acoustooptic; modulator; generates; achieve; adequate; separation; megahertz; apart; optical detector; single element; detector apparatus; detector array; electrical connection; detector element; local oscillator; single electrical; detector elements; two-dimensional detector; heterodyne detection; single-element optical; array element; /356/359/