关键词: 制冷型红外探测器/
f数/
球面反射温阑/
杂散辐射
English Abstract
Design of varying f/number of cooled infrared detectors based on spherical reflecting warm shield
Chang Song-Tao1,Tian Qi-Jie1,2,
He Feng-Yun1,
Yu Yi1,
Li Zhou1,2
1.Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;
2.University of Chinese Academy of Sciences, Beijing 100039, China
Received Date:13 March 2017
Accepted Date:10 April 2017
Published Online:05 August 2017
Abstract:As is well known, the f/number of a cooled infrared detector is determined by the aperture and position of the internal cold shield. Moreover, the f/number can be changed by inserting a warm shield in front of the detector. In order to reduce the stray radiation introduced by an ordinary planar warm shield, we propose a method of varying f/number of the infrared detector based on a well-designed spherical reflecting warm shield in this paper. First, an infrared radiation model is established in order to analyze the influence of the stray radiation introduced by the ordinary planar warm shield. Then the design principle of the spherical reflecting warm shield is put forward. By changing the surface shape and emission characteristics, the stray radiation introduced by the ordinary planar warm shield can be obviously reduced. Hence it is beneficial to maintain the performance of the detector effectively while the f/number is changed. To validate the proposed method, a spherical reflecting warm shield and an ordinary planar warm shield are designed to vary the f/number of a cooled infrared detector respectively. To compare the influences of the two warm shields on the cooled infrared detector, radiometric calibration experiments are conducted in a high-low-temperature test chamber. The analyses and experimental results show that the stray radiation of spherical reflecting warm shield is far less than that of the ordinary planar warm shield. Moreover, the noise equivalent temperature difference introduced by the designed spherical reflecting warm shield is lower. Therefore it is indeed better than an ordinary planar warm shield in ensuring the performance of an infrared imaging system.
Keywords: cooled infrared detector/
f/number/
spherical reflecting warm shield/
stray radiation
