CORRELATION-MEASUREMENT AND GROUP DELAY TRACKING IN OPTICAL STELLAR INTERFEROMETRY WITH A NOISY DETECTOR

The use of a noisy detector for group delay tracking and/or correlatio n measurement in optical stellar interferometry is analysed. Expressio ns are derived for the signal-to-noise ratio of correlation measuremen t and the probability of tracking loss in the presence of detector noi se. It is shown that such a detector can be suitable for either measur ement. For example, the high quantum efficiency of modern charge-coupl ed devices (CCDs) can offset the readout noise to a large extent, maki ng them a good candidate for use in fringe tracking.