Patent ID: 7022966

Claim:
A system for detecting a position of a light spot in a light distribution comprising: a first discrete response position sensitive detector (DRPSD) of length L 1 having a first prescribed number of photo-sensitive pixels for determining an estimate of the light spot position; a second discrete response position sensitive detector (DRPSD) of length L 2 having a second prescribed number of photo-sensitive pixels operating within a window of prescribed width approximately centered about the estimate of the light spot position determined by the first discrete response position sensitive detector, the length L 1 being substantially equal to the length L 2 ; means for receiving a photo-generated signal from each of the photo-sensitive pixels from the first DRPSD; and means for comparing the received photo-generated signals to determine which one of the photo-sensitive pixels from the first DRPSD has the highest photo-generated signal, the highest photo-generated signal being representative of the estimate of the light spot position; wherein the first prescribed number of photo-sensitive pixels of the first DRPSD is equal to 2 n , each being of a first prescribed pixel size; the second prescribed number of photo-sensitive pixels of the second DRPSD is equal to 2 k , each being of a second prescribed pixel size, where n≦k and the first prescribed pixel size being larger than the second prescribed pixel size.