Effect of the astigmatism of a thermal lens on the selection of the parameters of a laser with a wide-aperture adaptive mirror

The stability regions are determined for a cavity containing a wide-aperture adaptive mirror and an astigmatic thermal lens. It is shown that the thermal lens astigmatism is responsible for a strong reduction in the size of the stimulated emission region of a solid-state laser, particularly when the cavity is long. Experimental results demonstrate that at one of the boundaries of this region it is possible to generate a beam with a figure of merit of 2. It is shown that an adaptive mirror located near this boundary can be used as a corrector in a system for active stabilisation of the radiation power, which can lower the relative instability of the Nd³⁺:YAG laser radiation power to 0.5%.