Optimization of the shape of mirrors in a multipass pulsed laser amplifier with an optically inhomogeneous active medium

An analysis is made of the possibility of preliminary correction of the shape of mirrors for the purpose of compensation of optical inhomogeneities developing in a laser-active medium during pumping and stimulated emission. Specific calculations are reported for multipass CO amplifiers with the Cassegrain optics. It is shown that for pulse durations comparable with the time needed for the formation of pump-induced optical inhomogeneities of the active medium a small (up to 1%) change in the curvature of mirrors in a Cassegrain telescope makes it possible to reduce by a factor of 5–6 the average (during a radiation pulse) beam divergence at the amplifier exit compared with the case of strictly cylindrical (or spherical) mirrors.