Variable Curvature Mirror with Variable Thickness and Its Application in Space-Borne Optical Camera

A variable curvature mirror is a kind of active optical element. By changing its curvature radius, the corresponding wave-front could be dynamically controlled. First of all, the current situation and development trend of variable curvature mirrors are summarized systematically. After that, the physical model of deformation of variable curvature mirrors with variable thickness is established and the capability of this kind of variable curvature mirror in generating large saggitus and maintaining good surface figure accuracy is proven through numerical simulation and experiments. Finally, the application of variable curvature mirrors with variable thickness in space optical cameras is explored from three aspects. In the first place, in order to satisfy the requirement for the super large saggitus variation required by realizing large magnification ratio zoom imaging, a finite element alternating (FEA) based optimization procedure by incorporating high order spherical deformation is designed, and the mirror with the saggitus variation approaching 1 mm is obtained. In the second place, aiming at the requirements of focusing accuracy and speed in space camera imaging, a high-precision large dynamic focusing method based on sub-mirror variable curvature mirrors is proposed. In the third place, a coding imaging method using a variable curvature secondary mirror to scan quickly along the optical axis during integration time is proposed.