The Design And Optimization Of Highly Efficient Cold Shield In IR Detector

With the development of infrared technology and processing technology,the demand of IR detector performance is also promoted among each area,especially the large area infrared detector with high sensitivity and high temperature resolution.The performance of IR detector is easily affected by the stray radiation in working environment,causing the decreasing of SNR(signal to noise ratio)and imaging quality.Therefore,the analysis and suppression of stray radiation is critical to improve the cold efficiency of large array cooled infrared detector.Firstly,the research trends at home and abroad of cold shield efficiency improvement and the basic theories of stray radiation are briefly introduced in this dissertation.A detail discuss about stray radiation sources and corresponding suppression is also given,which make theoretically preparations for following work of stray radiation suppression in cooled infrared detector.Secondly,some methods of restraining stray radiation are suggested,and the principle of laying out vanes inside cold shield is also discussed thoroughly.In this section,a novel vane characterized by rounded-square hole is put forward.Moreover,a comparison between the original annular vane and the novel rounded-square vane is provided,demonstrating the advantage of the novel one in stray radiation suppression.Thirdly,the modeling and simulation details of the cooled infrared detector are also introduced,including the optical-mechanical structures,surface properties and sources and so on.Various structures of cold shield and vanes are simulated and analyzed by Advanced Systems Analysis Program(ASAP software),verifying that the retraining effect is variated by the change of the vanes and cold shield.In the meanwhile,parallel radiation is adopted to discuss about the suppression effect of stray radiation with different incident angles,and a modification of vanes is presented based on the simulation results.Moreover,not only is the uniformity of detector array analyzed,including solid angle,blackbody radiation and vanes,but several simulations are also presented.Finally,according to the experimental results,the cold shield with vanes get better performance in stray radiation suppression,and compared to the annular vane,the vane Moreover,some constructive advice for optimizing design of cold shield and vanes is proposed.