MODEL FOR THERMAL DISTORTIONS OF HIGH-ENERGY REPETITIVELY PULSED LASER MIRRORS

An analytical model for the thermal distortion of liquid-cooled high-power laser mirrors is presented, based on solutions to the heat conduction, elasticity, and dynamic plate bending equations. Results are presented for the temporal and spatial temperature distributions, normal distortion, and bending distortions due to nonuniform absorbed flux distributions, including sinusoidal, central obscuration, central heating, and astigmatism due to turning flats. Expressions were also derived for distortions due to coolant pressurization, and the optimum coolant heat-transfer coefficient is obtained. The peak dynamic stresses due to pulsed irradiation were also calculated. The results from the derived expressions are in good agreement with available data.