Cryogenic Blackbody Calibrations at the National Institute of Standards and Technology Low Background Infrared Calibration Facility

National Institute of Standards and Technology, Gaithersburg, MD 20899-0001 The Low Background Infrared Calibration Facility (LBIR) at the National Institute of Standards and Technology has been in operation for calibration measurements of ihe radiant power emitted fn>rn infrared radiation (IR) sources, such as cryogenic blaclcbodies, for more than 2 years. The IR sources arc sent to NIST by Customers from industiy, government, and university laborato^ii^s. An absolute ciyngenic radiometer is used as the standard detector to measure the total radiant power at its aperture. The low background is provided by a closed cycle helium refrigeration system that maintains the inner parts of Ihe calibration chamber at 20 K. The radiance temper* ature of the blackbody is deduced from the measured power and cottipared with the htackbody temperature sensor data. The calibration procedures and data analysts arc illustrated using the measurements of a typical blackbody.