Investigation of the mirror characteristics and optimisation of the cavity of a supersonic cw chemical laser emitting the first overtone of the HF molecule

The transmission and scattering coefficients of the cavity mirrors were determined at the wavelengths λ = 1.3 — 1.4 μm typical of the radiation emitted by an overtone cw chemical HF laser. The results obtained were used to formulate the requirements in respect of the quality of the optics (the reflection and scattering coefficients) and to propose optical cavity configurations for lasers with the active medium 40 and 70 cm long. These formulations and proposals were verified experimentally. The experimental small-signal gain was used in a numerical analysis of the influence of the mirror characteristics on the output power and the emission efficiency of overtone lasers of the investigated type. The optimal reflection coefficients of the output mirrors were determined.