星载大气痕量气体差分吸收光谱仪杂散光抑制

Stray light suppression of space-borne differential optical absorption spectrometer for monitoring atmospheric trace gas

考虑杂散光对星载大气痕量气体差分吸收光谱仪测量精度的影响,设计了遮光罩和其他消杂光结构来抑制杂散光,并对杂散光进行了分析。利用TracePro软件分析了系统紫外通道1(240～315nm)的杂散光水平,确定了杂散光传输的一次、二次散射路径。根据杂散光传输路径,计算了杂散光评价指标点源透射比(PST)曲线,结果显示杂散光抑制措施效果明显,PST小于3×10-5,中心视场杂散光照度水平为5.472×10-4,最终杂散光水平达到了设计指标要求。采用截止滤光片法测量了系统的杂散光水平,结果表明:中心视场杂散光比值为8.167×10-4,和仿真结果接近,验证了仿真过程的准确性,说明设计的消杂光机构能够满足抑制系统杂散光的要求。

In consideration of the effect of stray light on the measurement accuracy of a space-borne differential optical absorption spectrometer for monitoring atmospheric trace gases, several stray light removing mechanisms including a light shield and other baffles were developed to suppress the stray light, and the properties of the stray light were analyzed. With TracePro model, the stray light remo- ving of UV channel 1（240--315 nm） in the system was evaluated ,then the first and second order scattering paths were determined by simulation analysis. On the basis of stray light paths, the stray light removing for revised system was analyzed, and Point Source Transmittance（PST） was calculat- ed. The obtained PST value shows that the light shield and other mechanisms have suppressed thestray light effectively, PST values are less than 3 ×10^-4, and stray radiation ratio in a central field is 5. 472×10^-4. Furthermore, the final stray light suppressing level of the system satisfies the require- ment of design index. Moreover, the edge filter method is used to measure the stray light level, and the results indicate that the stray light in the central field is 8. 167 ×10^-4, which is close to the simu- lation results and proves the simulation result to be credible.