Field Tests And Signature Analysis Of An Imaging CO2 Laser Radar

A coherent, imaging CO2 laser radar has been built and tested in the field. This laser radar uses a single-waveguide CO2 laser and heterodyne detection. Two acousto-optic frequency shifters generate the IF frequency. An acousto-optic standing-wave device provides the 15 MHz intensity modulation used for ranging. The sensor includes a two-axis, dual-aperture galvonometer scanner with selectable field of view and depression angles. The optical system fits on an easily transportable 3 ft by 4 ft optical bench. Both reflectance and range images are produced. The range imagery analysis shows a range resolution of approximately one foot. Statistical analysis of the reflectance data from a military truck, the dirt ground, and an asphalt road shows that they are Rayleigh distributed. The reflectivities of these objects are determined to be around two percent through comparison with laboratory reflectometer measurements.