Coded-aperture x- or γ-ray telescope with least-squares image reconstruction. I. Design considerations

Publisher Website
Google Scholar
Abstract
Reconstruction of multiplex images produced by coded‐aperture telescopes for extended sources of radiation which cannot be reflected or refracted (moderate‐ to high‐energy x rays and low‐energy γ rays) can be accomplished by least‐squares solution of an overdetermined set of simultaneous equations linking the object, the aperture, and the image. A necessary condition is that the object field (an area of the sky) have a smaller number of pixels than the multiplex image recorded by the position‐sensitive detector, which requires that the projection of the object field onto the detector plane be smaller than the detector. This can be achieved by the use of an auxiliary completely open aperture of carefully chosen size and position (‘‘limiter’’) ahead of the coded aperature. The latter consists of regularly spaced elements which are made open or closed either randomly or according to some pattern, subject to solubility of the resulting set of equations. It may be larger or smaller than the detector, the undersize configuration having several advantages. A companion article [T. P. Kohman, Rev. Sci. Instrum. 60, 3410 (1989)] and supporting materials discuss various aspects of the implementation of the design for deployment on balloons or Earth satellites, describe a computer program developed for simulation of the operation of this telescope, and present the results of many simulations, which have demonstrated the feasibility of this approach to coded‐aperture imaging.

This publication has 63 references indexed in Scilit: