PULSED HETERODYNE CO2-LASER RANGEFINDER AND VELOCIMETER WITH CHIRP CORRECTION

A pulsed hybrid CO2 transversely excited atmosphere (TEA) laser has been used in a bistatic laser rangefinder-velocimeter system with heterodyne detection. Several techniques have been applied to improve the performance of the system. These include the stabilization of the hybrid CO2 TEA-laser and the stabilization of the frequency offset of the local oscillator (better than +/- 74 kHz peak to peak), phase-front matching at the detector surface resulting in a heterodyne beat efficiency of 0.4-0.6, and chirp correction. With this system, targets at distances of up to 25 km can be detected with an accuracy of 15 m. The velocity of the targets can be estimated with an accuracy of approximately +/- 0.5 m/s.