Signal properties and the optical parameter design of a laser radar

The 3 dB contrast criterion is suggested based on the statistical properties of the back-scattered signal light. In case of heterodyne detection, the signal light speckle size is considered to be a key parameter in the matching between the signal light and the local oscillator (LO) light. Furthermore, the angular discrimination of a scanning imaging laser radar (lidar) is concluded to be 0.75/spl Theta/ for heterodyne detection and 0.67/spl Theta/ for direct detection, where /spl Theta/ is the probe beam divergence angle. Based on these analyses, the relationship among the optical paramerers of a lidar is summarized, which may help us to design the optical system properly.