Laser physics and laser optics

Combined windows for high power gas lasers

M. V. Rogozhin.^a, V. E. Rogalin^b, M. I. Krymskii<sup>a

a</sup> Laboratory of Laser Navigation Systems, Moscow Institute of Physics and Technology, Dolgoprudnyi, Moscow oblast, Russia
^b Institute of Problems of Electrophysics of the Russian Academy of Sciences, St. Petersburg

Abstract: Based on the previously developed mathematical model of the behavior of the multi-kilowatt laser window with an unstable cavity, the case of a two-component output window is considered. The two-component window consists of a transparent polycrystalline diamond ring and a central opaque area separated by a plastic vacuum gasket. The central opaque area is equipped with a cryoaccumulator to reduce heat load. Numerical calculations of thermomechanical processes are performed for such windows used in high-power CO$_2$ lasers. Mathematical model used for the calculations consists of three parts – thermophysical, mechanical and optical. The advantages of using a two-component design with a cryoaccumulator under the conditions of a gas laser operating in the multi-kilowatt power range are demonstrated. The dependences of the maximum output power, temperature distribution and mechanical stresses versus the thickness of the window are obtained. The optimal conditions providing maximum radiation strength and minimum beam divergence are considered.

Keywords: exit window, high-power laser, divergence, thermal lens, material undergoing a phase transition during heating (MPT), and resonator.

Received: 16.09.2019
Revised: 21.06.2020
Accepted: 03.07.2020

DOI: 10.21883/OS.2020.11.50173.268-20

 English version: Optics and Spectroscopy, 2020, 128:11, 1837–1843

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