AN IMPROVED SAMPLING CONFIGURATION FOR A CODED-APERTURE TELESCOPE

The sensitivity of a gamma-ray coded aperture telescope has been studi ed in order to investigate the trade-off between angular resolution an d the reconstructed image signal to noise ratio (SNR) that occurs when a discrete pixel detector is used. Without fine sampling of the coded mask by the detector plane, the reconstructed SNR is seriously compro mised if the source under observation lies close to sky pixel boundari es, falling to as low as 25% of the maximum SNR. Fine sampling partial ly restores the image SNR, but at the expense of the telescope angular resolution. However, it is shown that the use of a non-integer fine s ampling value, for example 1.5 X 1.5 detector pixels per mask element, can be used to achieve high image SNR whilst retaining good angular r esolution.