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Two extended area reference blackbodies, covering temperature range from 100 K to 900 K, have been designed and built by VNTIOFI and Vega International, Inc., for Gennan Institute of Space Sensor Technology. The design objectives were to develop Plankian sources for high accuracy IR calibrations; provide, where possible, both high vacuum (10.6Ton) and atmospheric operation capabilities for easier achievable calibration traceability; and attain compact design to serve as a portable transfer Standard. Target technical specifications for the low temperature blackbody BB100 include 100 mm full aperture, 12° viewing angles, 0.999 effective spectral emissivity in 3 jim to 15 p.tm band, 100 K to 450 K temperature range, 50 inK temperature uniformity across aperture and, finally, 30 mK temperature setting/measurement accuracy.An employed design was selected after conceptual design study, which involved extensive thermophysical modeling and optimization. A finite element method has been applied to calculation of temperature distributions. Effective emissivity simulation was realized by the Monte Carlo method. The results of computer modeling of temperature distributions and effective emissivity are presented. Both target specifications and results of BB characterization are provided. Results of investigation confirm validity of selected approach and assumptions. Possibilities of further improvement of blackbodies performance are discussed.

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