Performance characterization of non-contact infrared thermometers (NCITs) for forehead temperature measurement

The ability to assess the performance of a non-contact infrared thermometer (NCIT) may be limited due to the algorithms necessary to predict a reference site temperature (e.g., oral) from a measurement of the forehead skin temperature. The algorithm not only adjusts for the difference between the reference site temperature and forehead temperature, but may also account for hardware corrections, bias adjustments and emissivity settings. These algorithms are proprietary to the manufacturer and can be unique for each device. ASTM E1965-98 (2016) is a standard test method for the evaluation of NCITs. It includes forehead thermometers; however, the algorithm must be known or an unadjusted calibration mode must be accessible. This study evaluates 6 NCIT models (10 units of each) against the ASTM standard error criterion using a blackbody source. Units were tested within the manufacturer's operating and temperature measurement range specification. A method to evaluate measurement outliers and characterize each model's performance when the adjustment algorithm is unknown is proposed. Using this method, 5 of the 6 models had a predicted error > 0.3°C.