Calibration of coherent lidar targets

Detailed measurements of moving hard targets were made. The bidirectional reflectance distribution function (or backscatter reflectance) at a 45-degree angle of incidence and observation was determined for circularly polarized radiation of lambda at 10.6 microns. The targets used were 120-grit aluminum oxide sandcloth and 400-grit silicon carbide sandpaper with a standard of sublimed flowers of sulfur. The effect of range and atmospheric effect of turbulence-induced beam wander are discussed for both rotating disks and linearly translated belts. The advantages of large slowly rotating disks for field calibrations are presented.