Phase control of HF chemical lasers for coherent recombination

A servo system for phaselocking two HF chemical lasers, operated on selected lines, was designed and simulated. A steady-state phase error is achieved that is adequate for coherent optical recombination. The results are based on the measured frequency drift of a small HF chemical laser and the measured frequency response of a piezoelectric transducer (PZT) mirror driver. A major innovation is the use of rate feedback with a laser Doppler sensor to extend the useful frequency response of the PZT driver. Closed-form expressions for the regulator gains derived by quadratic synthesis and state vector covariance are provided.