The effects of clipped photon detection in speckle interferometry and speckle masking techniques.
Résumé
This paper presents numerical illustrations of the effects of clipping of photoevents in speckle interferometry and speckle masking. The clipping is due to a saturation of the photon-counting detectors that cannot count more than one photon per pixel, causing the image to be composed of "0" and "1". The theoretical basis for this study has been published by Aime & Aristidi (1992). Clipping effects are investigated numerically on real star data. As predicted by theory, the clipping introduces several effects on auto and triple correlation functions, such as a linear global loss of energy, and non linear terms which affect mainly the high frequencies. Attention is focussed on the way the astronomical information is affected by this kind of detection, especially for the case of the double stars.