Freeform Surface Graded Optimization of Deformable Mirrors in Integrated Zoom and Image Stabilization System Through Vectorial Ray Tracing and Image Point Freezing Method

Integrated zoom and image stabilization system based on deformable mirrors (DMs) has advantages of miniaturization, rapid response and low energy consumption. Integrating the two capabilities on one DM-based imaging system poses considerable challenges. First, limited DM stroke will result in limited changeable aberration correction value for zoom and image stabilization. Second, the DM-based off-axis imaging system suffers a simple relative movement between optical axis and objects caused by carrier vibration may result in complicated optical system aberrations. To address these challenges, a reasonable assignment of the changeable aberration correction value for zoom and image stabilization is needed. Image stabilization and aberration correction in DM-based off-axis imaging system, should be considered when translation or rotation occurs. To troubleshoot the assignment issues of the correcting aberrations, we propose a graded optimization method which comprises two steps. To troubleshoot the image stabilization and aberration correction issues, we introduce vectorial ray tracing method and image point freezing principle to transform the aberration correction problem into an optimization problem of image coordinates. With the proposed method, we construct practical integrated freeform surfaces of DMs for a space camera with three mirrors. The sagittal heights of designed DM surface profiles are limited within their available stroke.

基于变形镜（DMs）的集成变焦和图像稳定系统具有小型化、响应快速和能耗低的优点。在一个基于变形镜的成像系统中集成这两种功能带来了相当大的挑战。首先，变形镜行程有限会导致变焦和图像稳定的可变像差校正值有限。其次，基于变形镜的离轴成像系统中，由于载体振动导致光轴与物体之间的简单相对运动可能会导致复杂的光学系统像差。为了应对这些挑战，需要合理分配变焦和图像稳定的可变像差校正值。在基于变形镜的离轴成像系统中，当发生平移或旋转时，应考虑图像稳定和像差校正。为了解决校正像差的分配问题，我们提出了一种分级优化方法，该方法包括两个步骤。为了解决图像稳定和像差校正问题，我们引入矢量光线追迹方法和像点冻结原理，将像差校正问题转化为像坐标的优化问题。利用所提出的方法，我们为一个三反射镜空间相机构建了实用的变形镜集成自由曲面。所设计的变形镜表面轮廓的矢高被限制在其可用行程内。