Image Quality With Narrow Beam Illumination In An Active Tracking System

The estimation of the angular position of an object and the evaluation of image quality are considered for an active tracking system consisting of an agile scanning transmitter and an imaging receiver. In many applications (e.g. imaging at long ranges) transmitter energy/pulse requirements are stressing, and flood illumination of targets will result in images that are severely degraded due to photon shot noise. In order to achieve better image quality and tracking accuracy, it may be preferable to scan a narrow beam over the entire object or an object feature. This may reduce the effects of shot noise, but would magnify the effects of beam jitter. In this paper, we examine the effects of these two sources of image degradation, and introduce various measures of image quality. The quality of the restoration of the degraded image is evaluated, showing the extent to which the effects of beam jitter and shot noise can be reduced. There exists an optimum beam size for which the quality of the restored image is best. The sensitivity of image quality to the selection of beam size is examined, and the effect of narrow beam illumination on the performance of various algorithms is discussed.