低温辐射计的结构优化方案设计

传统低温辐射计的布儒斯特窗口会对传递探测器的绝对光谱响应率定标产生较大的影响。文中阐述了低温辐射计对传递探测器的传统定标过程；分析定标过程中因布儒斯特窗口及窗口复现导致定标精度降低的原因；提出一种新的定标结构。该结构中低温辐射计和传递探测器安置于同心弧形轨道上，二者通过精密电机的控制可以分时切入定标光路，实现传递探测器相对于低温辐射计的绝对定标。新的定标结构能够完全消除布儒斯特窗口在传递探测器定标过程中的影响，降低测量激光功率约50%的不确定度，可以进一步降低辐射定标溯源基准的不确定度，提高定标的精度。

Optimization scheme design on construction of cryogenic radiometer

The Brewster window of traditional cryogenic radiometer has a great influence on the accuracy of absolute spectral responsivity calibration of standard transfer traps. In this paper, the traditional calibration for standard transfer trap was introduced. The reasons of precision degradation due to Brewster window and its state repeatability were analyzed, based on which a novel calibration scheme was proposed. The cryogenic radiometer and standard transfer trap were assembled on a concentric orbit and manipulated by an accurately electromechanical driving mechanism. By alternately switching the two instruments into calibration optical path, the absolute calibration for a standard transfer trap against cryogenic radiometer could be carried out. The new calibration system could completely eliminate the influences caused by Brewster window, would reduce about 50% uncertainty of laser power measurement and further reduce the uncertainty during the calibration process, which is of great significance in improving the accuracy of radiometric calibration.