Temperature uncertainty of IR thermal imager calibration

Widening uses of Infrared Thermal Imagers, many having temperature measurement indication, calls into question the accuracy of indicated temperature values. The answer is not simple since there are two separate and distinct areas that impact any measurement, calibration and actual use. The two areas can be treated separately, since they are, in fact, separate conditions of instrument use, one ideally under well controlled and highly repeatable conditions. This report covers the topics associated with calibration. First, there is a generic review of typical Infrared Radiation Thermometer measuring instrument methods. Next, practices reported in the literature for IR Thermal Imagers are presented. Then these are compared with actual procedures and practices used by imager manufacturers. This last information was gathered through voluntary responses to a survey of equipment makers.