High-Speed Photoconductive Hotbox Detector

Low resistance photoconductive element made from HgCdTe crystal is the sensor of high-speed photoconductive hotbox detector.The lens is made of Ge,and on the surface of the lens,the film is used to increase the transmissivity over 80%.Focus of the optics system is 25 mm and the relative aperture is F/1.5.In order to increase the sensitivity and detectivity of the detector,a three stage thermoelectric cooling device is adopted,and the temperature on the cool surface can be lowered to-65℃±0.02 ℃.For improving the anti-interference ability of the amplifier,the Differential Mode input with high common mode restraining technology is adopted in amplifier circuits.The detecting accuracy of the bearing temperature will be influenced by the changing of detector box temperature,so a temperature self-adapting system which consists of controllable heat source,Pt resistance,hot target,control circuit,heating power circuit,is installed.The detectors have been applied to speed-increase trunk lines in China,and the results are satisfying.