空间环境温度的变化对星载大气痕量气体差分吸收光谱仪光学系统成像质量的影响很大。以主镜组件为例，利用有限元方法对不同的温度分布形式，即均匀温度场及 3个方向温度梯度对主镜面形的影响进行了分析。通过对不同温度分布下主镜表面各点的变形量进行标准球面拟合，得到了面形 RMS值的变化规律，通过对比主镜面形公差的设计要求，确定了主镜正常工作所需的控温范围。其中均匀温度场的温度变化量需 ≤2℃，由于主镜对 Z向温度梯度分布相对 X向和 Y向更敏感，因此对热控提出了 Z向的温度梯度要求，而无需对 X向和 Y向温度梯度进行控制。

The change of ambient temperature greatly affects the image quality of the optical system in differential optical absorption spectrometer for atmospheric trace gas monitoring on satellite. For the primary mirror subassembly, the deformation of all nodes on the surface under different temperature distribution, including uniform field and temperature gradient in three directions, is calculated with FEA method and RMS values for surface error are obtained by standard spherical fitting. Finally, the range of temperature level for thermal control is got according to the RMS values and tolerance requirement. It is found that uniform temperature change should be less than 2℃ and the effect on surface error under the gradient in Z direction is greater than in X and Y direction, so the requirement of temperature gradient in Z direction is presented. The results provide the numerical basis for reasonable parameter of thermal control and reference data for other components in optical system.