Target reflectance measurements for calibration of lidar atmospheric backscatter data

Wavelength and angular dependence of reflectances and depolarization in the 9–11-μm region are reported for four standard targets: flowers of sulfur, flame-sprayed aluminum, 20-grit sandblasted aluminum, and 400-grit silicon carbide sandpaper. Measurements are presented and compared using a cw CO2 grating-tunable laser in a laboratory backscatter apparatus, an integrating sphere, and a coherent pulsed TEA-CO2 lidar system operating in the 9–11-μm region. Reflectance theory related to the use of hard targets to calibrate lidar atmospheric backscatter data is discussed.