Class of near-perfect coded apertures

Conference · Sat Jan 01 04:00:00 EST 1977

DOI:https://doi.org/10.1109/TNS.1978.4329301· OSTI ID:5267394

Cannon, T M; Fenimore, E E

Coded aperture imaging of gamma ray sources has long promised an improvement in the sensitivity of various detector systems. The promise has remained largely unfulfilled, however, for either one of two reasons. First, the encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. Second, if the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. It is proposed to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. In the case of a large detector background noise the URA will always do much better than the single pinhole regardless of the structure of the object. In the case of a low detector background noise, the improvement of the URA over the single pinhole will have a lower limit of approximately (1/2f)/sup /sup 1///sub 2/ / where f is the fraction of the field of view which is uniformly filled by the object.

• Research Organization: Los Alamos Scientific Lab., N.Mex. (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5267394
• Report Number(s): LA-UR-77-2369; CONF-771023-4
• Country of Publication: United States
• Language: English

Related Subjects

440101* -- Radiation Instrumentation-- General Detectors or Monitors & Radiometric Instruments
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
APERTURES
CAMERAS
CORRELATIONS
DATA PROCESSING
GAMMA CAMERAS
GAMMA SOURCES
IMAGES
NOISE
OPENINGS
OPERATION
PROCESSING
RADIATION SOURCES
SIMULATION