径向温度梯度对轻量化反射镜面形精度的影响

Influence of radial temperature gradient on surface figure of lightweight reflective mirror

为了分析径向温度梯度对轻量化反射镜面形精度的影响,以某空间相机2m口径轻量化反射镜为研究对象,建立了反射镜有限元模型,分析了不同分布形式的径向温度梯度对轻量化反射镜面形RMS的影响程度,通过试验验证了仿真方法及结论的准确性,研究了不同轻量化结构与径向温度梯度对反射镜面形精度的耦合影响。结果表明:不同分布模式的径向温度梯度引起的面形RMS值最大可相差294倍,且径向梯度引起的面形误差无法通过优化反射镜支撑方案的方式使其减小。不同轻量化结构的反射镜面形精度对不同分布模式的径向温度梯度敏感度不同,三叶式削边和对称式削边的轻量化方式在特定径向温度场分布模式下,会对反射镜热稳定性产生极不利影响。

To analyze the effects of radial temperature gradients on the surface figures of lightweight reflective mirrors, a 2-m-aperture lightweight mirror of a space camera was taken as the research object and a finite element model of the mirror was established. The effects of different radial temperature gradients and lightweight structures on the surface figure Root Mean Square (RMS) values of reflective mirrors was analyzed, and the accuracies of a simulation method and conclusions were verified through an experiment. In addition, the coupling effects of different lightweight structures and radial temperature gradients on the mirror surface figure were studied. Results show that the surface figure RMS values derived from the radial temperature gradients of different distribution modes can differ by a maximum of 294 times, and the surface shape error caused by the radial gradient is difficult to reduce when optimizing the mirror support scheme. The mirror surface figures of different lightweight structures are different for the radial temperature gradient sensitivities of different distribution modes. The lightweight methods of trefoil and symmetric chamfering are thermally stable to the mirror in a specific radial temperature field distribution mode. Finally, sensitivity has an adverse effect.