Modulated pulse lidar system for water frequency spectra measurements

Summary form only given. In modulated pulse lidar, a microwave subcarrier is superimposed on a blue-green optical pulse, transmitted through the water, and recovered by a high-speed photodetector and microwave receiver. This system enables one to transmit a microwave subcarrier underwater via a blue-green optical carrier to perform target detection and ranging. The system uses the harmonic content of a mode-locked, Q-switched, frequency-doubled Nd:YAG laser to obtain modulation frequencies from 0.5 to 10 GHz. The return signal is detected and digitized by a high-speed streak camera. This system will be used in controlled tank experiments to determine the effect of optical scattering and absorption on the modulated pulse and to identify system and environmental parameters that affect the ocean water frequency spectra.