Analysis of multi-factor on measurement improvement of an infrared imager in low-temperature environments

For infrared imagers, both measured temperatures (down -40.0 degrees C) and environmental ones (down -193.0 degrees C) might increase measuring error to an unacceptable level for practical applications. From the mechanism on temperature measurement of an infrared imager, the influences of the main factors (emissivity, environmental temperatures, and operating ones) on temperature measurement error were analyzed. A subsection multi-parameter model was developed from the calibration experiments of blackbodies. The theoretical error of measured temperatures from -40.0 degrees C to 160.0 degrees C was less than 2.0 degrees C under emissivity of 0.70-1.00, environmental temperatures of 193.0 to -65.0 degrees C, and operating temperatures of -10.0 to 15.0 degrees C. It was found that the operating temperatures caused larger temperature measurement error when the range of measured temperature was -40.0 to 60.0 degrees C. However, negative effects of operating temperatures could be ignored for measured temperatures from 60.0 to 160.0 degrees C. Furthermore, the calibration model was validated by graybody experiments under low temperatures. The maximum error was reduced from 7.8 degrees C to 1.4 degrees C under an emissivity of 0.90, environmental temperature of -193.0 degrees C and operating temperature of 10.0 degrees C. The results show that this multi-parameter calibration model effectively enhanced the measurement accuracy of an infrared imager for measured temperatures down -40.0 degrees C in low-temperature environments.