Non-Uniformity Correction in Microbolometer Array with Temperature Influence Compensation

Abstract

In the article a non-uniformity correction method is presented which allows to compensate for the influence of detector's temperature drift. For this purpose, dependency between output signal value and the temperature of the detector array was investigated. Additionally the influence of the temperature on the Offset and Gain coefficients was measured. Presented method utilizes estimated dependency between output signal of detectors and their temperature. In the presented method, the shutter is used for establishing signal reference. Thermoelectric cooler is used for changing the temperature of the detector array.

Temperature influence compensation in microbolometer detector for image quality enhancement

“…The previous research [7] shows that differences between following value of the RNU are rather inconsistent, for a constant GAIN table . Additionally value of calibration points used to calculate GAIN coefficients has bigger impact on the RNU value than a temperature drift of detector.…”

“…Therefore it is very important to find out what is the relationship between the NUC coefficients and non-uniformity of a corrected image during temperature changes of the detector. Impact of the detector array temperature on correction quality were specified on the basis of registration prepared at a laboratory test bench with an infrared camera and a black body [7]. Temperature of the microbolometer detector was set and stabilized by a thermoelectric cooler.…”

“…The influence of the cases temperature on the output signal of the detector can be measured in climatic chamber by changing environment temperature with constant temperature of the detector and a black body [3].…”

“…The first case needs considerable amount of energy. The second one needs reference target and some mechanical procedure to place the target at the front of the detector [3,6]. Additionally during calibration the reference target (shutter) blocks the radiation from the scene interrupting measurements with such thermal camera.…”

“…In this case detector is exposed to radiation coming from observed scene (or shutter during calibration), and lens [6]. The research presented in the article [3] shows that ones have to determine the factors for compensating influence of the lens temperature change on the detector output signal. The addition of the lens coefficients allows to separate a phenomenon of detector temperature influence from the lens (camera housing) influence.…”