A new method on improving the temperature operating characteristic of the uncooled infrared detector

Abstract

Because of its low-cost low-volume and little power waste , The uncooled infrared detector has widely used in military and civil affairs. But the imaging quality of the uncooled infrared detector is degraded badly even the image is not identified when the ambient temperature of the uncooled infrared detector is above 60 or under 0.Aim at this problem, a method of the local temperature control of the detector was proposed to improve the imaging performance of the uncooled infrared detector when its ambient temperature had a large dynamic range. A heat insulation structure between the detector and the readout circuit and the temperature control circuit based on pettier effect are designed. The pettier is wrapped around the detector and the temperature sensor is set in the detector. When the ambient temperature of the detector is range from -40 to 20 or from 30 to 70 the control circuit work and It can keep the ambient temperature of the detector about 30±5 .When the temperature is range from 20 to 30the control circuit do not work. By this design the ambient temperature of the detector is controlled near 30,so the detector can operate in the optimal temperature point recommended by manufacturer and the image quality can be hold in well. Based on the Sofradir 320×240 microbolometer ,above-mentioned method is used and the test prototype is made. The interesting experiments are done and the experiment results indicate that the method is feasible, effective, and can obviously extend the ambient temperature dynamic range for the practiced application of the uncooled infrared detector. In this paper, firstly Relations between the performance of the uncooled infrared detector and the operating temperature were analyzed simply. Secondly the method of local temperature control and the principal on how to improve the performance are described in detail. Thirdly the test prototype is introduced. Lastly the experiment results are given and some conclusions are discussed. Keyword: uncooled infrared detector, pettier effect, microbolometer ,temperature control