SYSTEM FOR TRANSMITTER FREQUENCY CONTROL IN COHERENT LADAR

摘要

SYSTEM FOR TRANSMITTER FREQUENCY CONTROL IN COHERENT LADAR A system for ensuring that the transmitted pulse of a coherent ladar is at the correct frequency for coherent detection of received echoes. A hybrid laser transmitter has its continuous mode signal frequency swept through the stabilized frequency of a local oscillator laser. At the instant when the frequency of the transmitter is at a predetermined difference with the frequency of the local oscillator, a high powered output signal is pulsed in the hybrid laser. The resulting reflected, received signals can be mixed with the continuous local oscillator signal in a crystal mixer to produce pulses at the intermediate frequency for amplification and detection. The effect of random variation in frequency of both the local oscillator and hybrid laser is thus avoided.