Time-resolved and energy-resolved coded aperture images with URA tagging

Journal Article · Wed Jul 15 00:00:00 EDT 1987 · Appl. Opt.; (United States)

DOI:https://doi.org/10.1364/AO.26.002760· OSTI ID:6489866

Fenimore, E E

Coded aperture imaging with uniformly redundant arrays (URAs) is the standard technique for imaging above the limit of grazing incident x-ray telescopes. It is an ideal technique for high energy astrophysics because it has high throughput, excellent performance on point sources, and the ability to measure simultaneously signal and background. However, many sources of interest in high energy astrophysics are time variable or require detailed energy spectra. Until now, to obtain a single time (or energy) sample, the photons from the particular time (or energy) interval must be formed into an encoded pattern, then processed to obtain an image for that sample. Therefore, massive computations are required to cover the entire time and energy parameter space. We present a new method of coded aperture analysis called URA tagging, which provides time and/or energy resolved histories of sources with known positions without using a correlation operation. It can easily reduce the computation time by orders of magnitude compared to the next fastest method, the fast delta Hadamard transform. URA tagging can also correct for improperly encoded images or motion blurred images. Whereas previous methods for quantifying performance have not taken into account the finite resolution or the quantized sampling, URA tagging provides a SNR equation that includes all such effects. URA tagging analysis explains why delta decoding has a somewhat poorer SNR than balanced correlation; naively, one expects the better angular resolution to yield a better SNR. In addition, we show that complementary URAs (exchange opaque and transparent elements) have different properties, and those with an even number of transparent elements should be preferred.

• Research Organization: Los Alamos National Laboratory, Los Alamos, New Mexico 87545
• OSTI ID: 6489866
• Journal Information: Appl. Opt.; (United States), Vol. 26:14
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
IMAGE PROCESSING
ALGORITHMS
SIGNAL-TO-NOISE RATIO
ASTROPHYSICS
COMPUTER CALCULATIONS
ENERGY SPECTRA
LASL
MONTE CARLO METHOD
NUMERICAL ANALYSIS
NUMERICAL SOLUTION
OPTIMIZATION
PERFORMANCE
TELESCOPES
TIME RESOLUTION
MATHEMATICAL LOGIC
MATHEMATICS
NATIONAL ORGANIZATIONS
PROCESSING
RESOLUTION
SPECTRA
TIMING PROPERTIES
US AEC
US DOE
US ERDA
US ORGANIZATIONS
657002* - Theoretical & Mathematical Physics- Classical & Quantum Mechanics
990230 - Mathematics & Mathematical Models- (1987-1989)