月基对地观测极紫外相机光机结构设计

Opto-mechanical design of lunar based EUV camera for imaging the earth

为了实现从月球表面对地球周围等离子体层进行长期观测,给出了一种有效可行的实现方案:采用单球面反射镜与球面探测器组成光学系统,视场角14°,空间角分辨率小于0.1°;采用地平式二维转动机构以实现对成像镜筒组件俯仰、方位的调整,保证对地球的瞄准和跟踪。重点对主反射镜支撑结构和转动机构给出了较为详细的设计。有限元分析和试验表明,光机系统选材合理,焦平面稳定性好,反射镜支撑结构合理,镜面面形在ΔT=50℃温降载荷下≤14nm;二维转动机构动态刚度较高,结构紧凑,整机重量≤16kg,在要求的温度变化范围内运转正常。

In order to monitor the changes in plasma density and distribution through imaging the Earth plasmasphere, an effective implementation solution is presented, in which the optical system consists a single spherical mirror and a spherical surface detector, and has a field of view of 14 degrees and angular resolution of less than 0.1 degree. A 2-D adjusting mechanism for tracking and pointing the earth is designed to realize the pitch and azimuth adjustment of the imaging apparatus, which consists of horizontal shaft module and vertical shaft module, and ensures the aiming and tracking of the apparatus to the earth with pointing accuracy better than 0.1°. The structure design of the mirror supporter and adjusting mechanism is given in detail. FEM simulation analysis and experiment indicate that the structure of the reflector has both high rigidity and fine stability; the surface accuracy of the reflector meets the requirements of imaging quality （PV value is less than 14 nm）. Vibration and thermal tests were carried out; test results show that the mechanical design of the adjusting mechanism has adequate eigenfrequencies, stiffness and strength, and better space environmental adaptability. Imaging performance test shows that the optical system meets the requirements of EUV detection in the science goal of the Chang＇e Engineering.