The NIST EOS Thermal-Infrared Transfer Radiometer

A portable Thermal-Infrared Transfer Radiometer (TXR) has been developed for use in intercomparisons and scale verifications of sources used to calibrate thermal-infrared (TIR) channels of the National Aeronautics and Space Administration’s (NASA’s) Earth Observing System (EOS) flight instruments. The TXR is designed to measure the radiance temperature of large area blackbody sources in cryogenic vacuum environments, either at the National Institute of Standards and Technology (NIST) or at the EOS instrument calibration facilities. It can be operated in ambient conditions of room temperature and pressure, or in EOS instrument thermal/vacuum chambers at temperatures as low as 77 K. The TXR is a liquid-nitrogen cooled filter radiometer with two channels: one centered at 5 μm based on a photovoltaic InSb detector, and the other centered at 10 μm based on a photovoltaic HgCdTe (MCT) detector. The spectral, spatial and temporal characterization of the TXR using state of the art NIST ambient infrared instrumentation is reported.