中小型圆形反射镜检测支撑优化

为了优化中小型圆形反射镜在加工、镀膜、装调等阶段的检测中所需的支撑结构,以V型块支撑工作原理设计了支撑位置及支撑点夹角均可调整的分体式支撑。利用有限元方法得到TMA系统中Φ136 mm非球面次镜面形随支撑点夹角的变化趋势,并根据趋势曲线,确定支撑点夹角为100°状态下,分体式支撑结构引起的镜面面形变化最小(RMS=0.57nm)。利用干涉仪结合补偿器的检测方式,对分体式支撑在不同的支撑点夹角下的镜面面形进行检测。所得结果与有限元方法得到的镜面面形随支撑点夹角变化趋势与试验结果相符,且在100°时分体式支撑引起的镜面面形变化(RMS=0.015 wave)明显优于其他角度。再以不同的镜坯材料及反射镜直径尺寸进行仿真对比,结果表明:镜面面形随支撑点夹角的变化趋势与反射镜材料和尺寸无关,趋势曲线幅值随材料弹性模量和反射镜直径改变而变化。优化得到的分体式支撑对于中小型圆反射镜具有广泛适用性。

Detection support optimization of small and medium round mirror

In order to optimize the support structure of small and medium round mirror during the processes of manufacturing,coating and assembling,the split-type support was designed,whose support position and support angle were adjustable,on the basis of V-block support principle.The trend curve that surface shape changed with support angle of Φ136 mm non-spherical TMA secondary mirror was obtained by FEM method.According to the trend curve,the optimized support angle that equaled to 100° was determined,which the surface shape that split-type support aroused reached the minimum(RMS=0.57 nm).The surface shapes corresponding to different support angles of split-type support were measured via interferometer combined with the compensator.The result shows that the trend curve obtained by FEM method well meets the trend curve obtained by interferometer,and the surface shape aroused by split-type support reaches minimum at the support angle of 100°(RMS=0.015 wave),which prevails the other angles.Compared with the mirror of different glass blank material and different diameter,the FEM result shows that the glass blank material and diameter are unrelated to the trend,but the trend curve amplitude changes with them.