Photo-EMF-based adaptive detectors as optimal photodetectors for detectionof light-pattern displacements

It is shown that non-steady-state photo-EMF-based adaptive photodetector op erates like an optimal detecting medium when detection of a general spatial shift of a complicated light pattern is needed. This detecting medium can be considered as some spatial distribution of photo-induced p-n junctions m atched with the: original light pattern and its sensitivity is limited basi cally by the thermal (Johnson) noise of the detector volume itself.