Speckle Effects on Statistical Performance of Optical Radar

The statistical performance of optical radar using energy detection techniques has been studied in this paper. The analytical expressions of the speckle number subtended by the receiving aperture are derived. The results show that the speckle number is only determined by the relative size of the speckle cell and the area of the entrance pupil. The receiving aperture will integrate a considerable number of speckle cells when the beam expander is not adopted in the transmitting optical system. Few speckle cells will be intercepted by the aperture when the beam expander is employed and the laser speckle is expected to be the dominant noise source. The detection performance of airborne and space-based optical radar has been analyzed based on two critical parameters--the speckle number and the average photoelectron counts. The probability density function of photoelectrons and the detection probability are derived for a number of occasions.