Experimental and numerical investigations on cooling performance of chemical-vapor-deposited SiC deformable mirror for adaptive optics system in high-power laser radiation environments

Abstract

• A large-diameter CVD SiC U-WDM for use in AO systems utilizing an HPLR system was presented. • The cooling performance of the CVD SiC U-WDM was investigated under HPLR conditions. • Fluid-thermal-structural coupling characteristics of the CVD SiC U-WDM were analyzed. • The CVD SiC U-WDM dramatically decreased the thermal deformation to submicron scale. In an adaptive optics system combined with a high-power laser radiation (HPLR) system, the thermal deformation of a deformable mirror (DM), which is induced by high-energy irradiation, is a significant factor influencing the optical performance of the system. In particular, the thermal deformation of the DM with a large diameter of more than a few hundred millimeters should be controlled to be on the order of 1 μm in various HPLR environments. To satisfy these challenging criteria, we experimentally and numerically investigated the cooling performance of a large-diameter water-cooled DM (WDM) with U-shaped cooling microchannels (U-WDM) made of chemical-vapor-deposited SiC, which was designed first in our previous research. The fluid-thermal-structural coupling characteristics of the U-WDM were verified and analyzed through the verification process. In addition, the fluid-thermal-structural coupling characteristics of the DM and U-WDM were compared and analyzed by applying four different HPLR conditions: annular, circular, holed-square, and square beams. Under all the HPLR conditions, the comparative study demonstrated that the U-WDM had dramatic cooling performance, reducing the thermal deformation by more than 85% compared to that of the DM and achieving submicron-scale thermal displacement, which was lower than the targeted actuator deformation limit of 1.3 μm.