用于超低温环境的轻质反射镜制造技术

以椭圆形平面反射镜实例为研究对象，介绍了轻质反射镜材料的选择以及反射镜在真空超低温环境中的应用。分析了各种轻量化孔的特点，设计了一种反射镜结构；在吊带支撑方式下，建立整体结构的有限元模型，对由于镜体自重及超低温环境引起的镜面变形进行了有限元分析。由数控系统在图形方式下控制实际轻量化加工，加工后的反射镜轻量化率达到33％；采用化学方法消除加工过程中产生的应力与微小裂纹；运用环形抛光机结合局部修磨进行光学抛光加工，抛光后面形精度达到0．022A（均方根，λ=633nm）；在实验室进行小范围温度拉偏实验，实验结果表明，面形精度变化量为0．03nm。

Manufacturing technologies of lightweighted mirror applied to vacuum cryogenic environment

The design and manufacture of an elliptic mirror used in remote sensing was described in detail. How to choose the materials of a lightweighted mirror was discussed and the applications of the mirror to vacuum cryogenic environments were introduced. Based on the analyses of effects of different shapes of lightweighting holes, the structure of mirror was designed. By supporting the mirror with a belt hanging system, the gravity effect and the ultra low temperature effect were analyzed with a finite-element software. Furthermore, the practical lightweighting manufacture was carried out in the routing function of a computerized numerical control machining system, and the lightweighting ratio of elliptic mirror obtained has exceeded 33%. In order to eliminate the residual stress and microcracks introduced in the process, the mirror was disposed by a chemistry etching, and processed by a zone polishing machine on local. Results show that the surface error after polishing reaches 0.022λ(rms, λ=633 nm). The experiment of temperature variation was done in a small range and the change of surface error is 0.03 nm.