Low-Temperature Calibration of Infrared Thermometers

Abstract

A method was developed for calibrating infrared thermometers to properly measure target temperatures ranging from ?70 to 0°C. Once calibrated for this range, the thermometer can then be used to measure the flux of thermal radiation from the sky. Salient features of the method include using dry ice in ethanol to cool a blackbody cavity, dry nitrogen gas to minimize condensation, and a fan plus insulation to keep the temperature of the infrared thermometer close to ambient.