Third Generation Water Bath Based Blackbody Source

摘要

A third generation water bath based blackbody source has been designed andconstructed in the Radiometric Physics Division at the National Institute of Standards and Technology, Gaithersburg, MD. The goal of this work was to design a large aperture blackbody source with improved temporal stability and reproducibility compared with earlier designs, as well as improved ease of use. These blackbody sources operate in the 278 K to 353 K range with water temperature combined standard uncertainties of 3.5 mK to 7.8 mK. The calculated emissivity of these sources is 0.9997 with a relative standard uncertainty of 0.0003. With 50 mm limiting aperture at the cavity; entrance, the emissivity increases 0.99997.