大口径离轴长条形反射镜的检测支撑机构

针对大口径离轴长条形反射镜光轴水平向检测的需要,设计了一套检测支撑结构。优化了结构参数,实现了由支撑结构引起的镜面面形误差最小化。通过比较长条形反射镜光轴水平向检测支撑的级联多点支撑结构,选择了结构简单、扩展性和调整性优良的两点单层固定支撑结构。利用集成仿真与优化方法,分析计算反射镜镜面面形误差随支撑间隔的变化趋势,确定了最优支撑间隔。最后,利用干涉仪结合补偿器的检测方式,对不同支撑间隔工况下镜面面形进行检测,验证了仿真分析的可靠性。结果表明:在支撑间隔为564mm时,由检测支撑引起的镜面面形误差最小(RMS=8.26nm),干涉检测得到的镜面面形误差随支撑间隔的变化趋势与仿真得到的趋势相符,仿真结果可靠性高。提出的方法可实施性好,可推广到其他大口径离轴长条形反射镜的设计和检测中,为离轴三反(TMA)相机的设计提供技术基础。

Detection support structure of large-aperture off-axis rectangular mirror

A detection support structure was designed to meet the need of a large-aperture off-axis rectangular mirror at an optical axis horizontal situation. Structure parameters were optimized to minimize the surface shape error caused by the detection support structure. Through comparing different cascaded multipoint lever support structures, a two-point support structure with simple structure, good extensibility and adjustment was chosen. Then,an integrated simulation and optimization method was used to analyze the trend curve of mirror surface shape changed with support interval and to obtain the optimized support interval. Finally, an interferometer combined with a compensator was used to measure the surface shapes corresponding to different support intervals and to verify the reliability of the simulation result. The result shows that the surface shape error caused by detection support structure reaches minimum at the support interval of 564 mm (RMS=8.26 nm), the trend curve obtained by simulation method agrees well with that obtained by the interferomety and shows a higher reliability. The method in this paper can be extended and applied to the design of detection support structure for other large aperture off-axis rectanglur mirrors, and can provide a foundation for off-axis Three Mirror Anastigmat (TMA) cameras.