风云二号辐射计百叶窗式遮光罩杂散光抑制研究

Stray light suppression in FY-2 radiometer with shutter

风云二号卫星扫描辐射计为视场分光方式的R-C光学系统,视场外的杂光掠过次镜穿过主镜孔直接混入信号光路照射在焦面上,形成直射杂光。为了消除该直射杂光,使用TracePro软件对辐射计模型进行正追和倒追,都追到了直射杂光的存在,利用Zemax软件仿真找出了该直射杂光的形成机理,并计算出该直射杂光域。根据仿真和计算,设计了可以透信号光阻挡杂散光的叶片状次镜遮光罩。软件仿真表明:百叶窗式遮光罩可以彻底抑制该区域可见直射杂光,积分球实验也验证了该百叶窗式遮光罩可以降低辐射计95.2%的可见杂光。

FY-2 radiometer is a multi-field Ritchey-tShretlen（ll-C） optical system.Stray tight outbmc the field grazes the secondary mirror, then goes across the primary mirror, and finally hits the detec tor, which produces the straight hit path. To eliminate this straight hit, we used Tracepro software package to trace the path and used Zemax software package to find out the generation mechanisms of it, and then calculated the area of the straight hit. Based on the simulation and calculation, a shutter with some laminas was designed, which could allow signal light to transmit but prevent the stray light entering into the detector. Results of the simulation illuminate that the direct stray light in this area can be eliminated completely by using the designed shutter. Also the integrated sphere experiment indicates the shutter can decrease 95.2% of the visible stray light.