The simulation of thermal deformation on lightweight optics with thick coatings

Lightweight optics utilized in high-power laser system can dissipate heat better and reduce system weight. Dielectric films can be designed for laser pulse modulation, high reflect rate and wide bandwidth. However, the deformation caused by coating residual stress will be large due to the large thickness of dielectric films and low stiffness of lightweight mirror, which brings a large bending deformation with the temperature variation. The traditional surface compensation technology is double-sided coating, but it is not suitable for lightweight mirrors. In this study, we construct a finite shell-element model to estimate the surface shape error caused by dielectric film coating residual stress on a lightweight mirror for surface pre-processing. Thermal deformation and bimetal effect deformation are also simulated.