大型空间反射镜发射率测量及误差分析

为了准确测定空间相机主镜毛坯件的表面发射率以便定量分析相机热控效果,本文在分析热像仪测温原理的基础上,利用现有测量条件,提出一种利用两种已知发射率材料作为参考的发射率测量方法.根据测量试验,得到主镜表面发射率为0.565.为定量反映各因素对测量精度的影响,对测量公式进行了误差分析.分析结果表明,与被测件表面发射率接近的材料的热像仪测温误差及发射率标称误差对测量精度有较大影响,同时得到本次试验因热像仪测温误差及参考材料发射率标称误差带来的测量误差为±0.028.最后,结合相机热平衡试验的数据对测量结果进行了验证,结果表明测量得到的主反射镜的发射率基本反映了热平衡试验的主镜表面状态,证明本文的方法对主反射镜发射率的测量是适用有效的.

Emissivity measurement and error analysis of large space reflector

To determine the emissivity of the primary mirror in a space camera and to analyze the thermal control effort for a subsystem,a method for measuring emissivity by using two kinds of materials with known emissivity as references was proposed based on the analysis of temperature measurement principle of a thermal imager.According to the emissivity measurement experiment,the primary mirror emissivity was calculated to be 0.565.To determine the influence of different measuring factors on the measurement accuracy,an error analysis was carried out.Analysis results prove that when the materials to be measured have almost the same emissivity with the objects,the temperature measurement errors of the thermal imager and emissivity standard error of the material will have greater impacts on the measurement accuracy.The measurement error caused by temperature measurement error and emissivity error is ±0.028 in the proposed experiment.Finally,the thermal model of the camera was modified by using a thermal equilibrium test,the results demonstrate that the emissivity measured by proposed method reflects the actual state of the primary mirror,and the method is useful and feasibility for measuring the emissivity of primary mirrors.