Time dependence of the divergence of the radiation emitted by a rhodamine laser pumped by a pinched discharge

It was found experimentally that the time dependence of the divergence of the radiation emitted by a rhodamine-6G laser, pumped by a pinched discharge, was governed by three factors: the propagation in the dye cuvette of ultrasonic waves generated by the pumping radiation; the distortions of the resonator as a result of nonuniform evolution of heat; the diffraction of light by the ultrasonic waves. The ultrasound was also observed when the cuvette was filled with air. Therefore, one should expect the generation of ultrasonic waves in the case of strong optical pumping of gas and liquid lasers.