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With the development of infrared remote sensing technology, a high detection accuracy is required for infrared remote sensing loads. For example, when measuring climate change, the sea surface temperature needs to meet the measurement accuracy of 0.1 K and stability of 0.04 K decade-1. High emissivity spaceborne blackbody radiation sources are important devices for infrared value traceability by providing accurate infrared radiation to calibrate infrared load. Emissivity is an important indicator of blackbody. It increases if the structure of the blackbody supports it and if there is a high emissivity coating. The Cross-track Infrared Sounder (CrIS) and Infrared Atmospheric Sounding Interferometer (IASI) are currently the infrared remote sensing loads that have a high quantitative level on the orbit. The internal calibration source of the CrIS is a spectral trap blackbody with an emissivity of 0.995. The internal reference blackbody of the IASI is a cavity blackbody with an emissivity not less than 0.996. The spaceborne blackbody for the infrared hyperspectral atmospheric detector of the Fengyun-3E satellite is also a cavity blackbody and its emissivity can extend beyond 0.996. Previous studies have shown that it is difficult for the emissivity of spaceborne blackbody to reach the level of 0.999. To meet the needs of the radiation calibration accuracy needed for infrared remote sensing, we proposed a highly emissive blackbody that uses a cubic reflection and absorption method based on light capture. We carried out an emissivity simulation based on ray tracing, and analyzed the influences of specular reflection, near specular reflection, and diffuse reflection on the emissivity of the blackbody. Two blackbodies with near specular reflection and diffuse reflection were fabricated, simulated, and tested experimentally; the experimental and simulation results were consistent. The blackbody whose surface reflection component was near specular reflection had a better light capture ability in the range of 8~14 μm, and it could achieve a higher emissivity (0.999) and lower uniformity.
Topic : Theme 1: Earth Energy Balance.
Reference : T1-C21
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