Long range optical communication systems have a difficult pointing and spatial acquisition problem to overcome. Receiver acquisition is generally accomplished by some type of search to determine the direction of arrival of the transmitted optical beam. In this study, several optical acquisition techniques are compared in terms of time to acquire, receiver complexity, desired accuracy, aryl signal and noise power levels. Computed curves indicating the relative trade-offs are presented. The advantage of acquiring with arrays of detectors placed in the receiver focal plane is shown. Although some problems exist concerning their fabrication, such arrays would allow for the implementation of sequential and parallel search algorithms that can theoretically greatly reduce acquisition time. Such a capability can make arrays an extremely powerful device in future generation optical trackers. In general, improvement increases as the array size increases, but it is shown that the size of the array need not be very large before a significant reduction in search time is achieved over standard spatial search techniques. Implementation difficulties associated with detector arrays are discussed. The use of arrays to obtain rapid zoom capability is also suggested and examined.
"Improved Optical Tracking And Acquisition With Detector Arrays", Proc. SPIE 0069, Optical Design Problems in Laser Systems, (24 November 1975); doi: 10.1117/12.954560; https://doi.org/10.1117/12.954560