Finite element analyses of thermal distortions of mirror substrates for high power lasers

The thermal distortions of mirror substrates with such materials as silicon, copper, tungsten and beryllium oxide are calculated and analyzed by use of finite element methods. The results show that when the power of input laser with the diameter of 17 cm gets up to 2 kW, and the reflectivity of the mirrors is 93%, the central maximum thermal distortions of the mirror substrates are separately 0.984 μm, 3.32 μm, 1.55 μm and 1.88 μm, respectively, under the radiation time of 10 seconds. By comparison, the thermal distortion of silicon substrate is the smallest, which would be a kind of more promising material for mirror substrates. And the thermal deformation of Cu substrate is the largest, while those of W and BeO are between Si and Cu. But the materials of W and BeO have high force int