Multiplex advantage in the detection of optical images in the photon noise limit.

This paper contains a theoretical comparison of the performance of a single, optically multiplexed detector with a set of independent scanned detectors in the measurement of optical images in the signal-dominated regime. The difference between the uncorrelated counts received in two channels-one corresponding to the required signal, the other to the background only-is analyzed as the signal estimator. Correlated counts, where identical photodetections are added to each channel, do not affect the accuracy of the signal that is described in terms of a SNR. The theory is confirmed by detailed experimental measurements of signal and noise. The results show a multiplex power advantage over a single scanned detector in the photon-noise limit of 1/4R, where R is the ratio of the mean signal per element over the entire image to the signal in the element under consideration. Thus, for instance, for a bright star in a dark field a 100 x 100 multiplex system would be equivalent to 2500 parallel detectors.