为满足空间遥感器在轨辐射定标精度和溯源性的需求, 中科院长春光机所研制了空间低温绝对辐射计。本文介绍了实验室辐射基准的低温辐射计的发展现状, 并着重介绍了我们研制的空间低温绝对辐射计的设计方案。空间低温绝对辐射计采用斯特林机械制冷机提供20 K工作环境, 通过优化吸收腔结构和热连接, 设计出响应度0.2 K/mW和1 K/mW的总腔和光谱腔。采用闭环高精度温度控制和两次电定标的电替代测量方式, 利用探测器材料在低温下的优异热性能, 实现总腔0.02%精度水平的光功率测量, 建立辐射基准。并采用温度比对的方式, 将辐射基准传递给光谱腔, 实现溯源至国际单位制基本单位的光谱辐射测量, 为遥感器在轨可溯源的光谱辐射定标提供重要的技术储备。

The space cryogenic absolute radiometer (SCAR) is developed at Changchun institute of optics, fine mechanics and physics, in order to satisfy the demands of accuracy and traceability of onboard radiance calibration of spaceborn remote sensors. In this paper, the design decision of SCAR was introduced with emphasis, based on the brief introduction of the state-of-the-art of the cryogenic radiometer benchmark. The working environment of 20 K of SCAR was supplied by a stirling-type cryocooler. The responsivities of total cavity and spectral cavity were designed to be 0.2 K/mW and 1 K/mW by optimizing the structures of cavities and thermal links. The radiance benchmark can be founded by the optical power measurement of 0.02% accurate, which was ensured by close-loop high precision temperature control and electrical substitution measurement procedure with twice electrical heating, as always as the excellent thermal properties of detectors at low temperatures. The radiance standard was transferred to the spectral cavity through temperature comparing, in order to realize the traceable spectral radiometric measurement. This work affords technical reserve for the traceable spectral radiance calibration of spaceborn remote sensors.