Research On Lead Salt Infrared Photoelectric Detector And Its Signal Processing System

Along with the continuous development of infrared detection technology,infrared photoelectric sensors have been more and more widely used in military and civilian applications.Lead-salt infrared photoelectric sensors prepared from lead selenide(Pb Se)and lead sulfide(Pb S),which are representative group IV-VI compounds,have the advantages of uncooling,small size and low cost.These materials have gained wide application in infrared detection in the mid-infrared band(1-5 μm).Infrared photoelectric sensors comprise two primary components: an infrared photoelectric detector and a signal processing circuit.However,these components face a critical bottleneck in the high-end field.Presently,China’s lead salt infrared photoelectric detectors and signal processing circuits predominantly rely on imports and relatively expensive.Therefore,it is crucial to explore alternatives that can bridge this gap in the field of infrared detection technology.Based on the previous research of the research group on lead-salt photoelectric thin film materials and chips,this paper focuses on the fabrication process of unit and small pixel surface array detectors and the signal processing system.The primary results of this study are as follows:(1)Based on the lead sulfide and lead selenide optoelectronic thin films developed by the research group,lead salt infrared photodetector chips were prepared by photolithography process and magnetron sputtering electrodes,and face-array PCB boards were designed.Then the chips were packaged to obtain the unit detector and 8-element face-array detector,which provided device support for the subsequent research and testing of the detector signal processing system.(2)For the problem of signal amplification and noise suppression of lead-salt infrared photodetector,this paper designs a signal suppression amplifier circuit.This circuit combines RC filtering and negative feedback amplification through the basic theories of weak signal amplification and noise suppression,combined with the signal characteristics of lead-salt infrared photodetector.It is found that the circuit effectively reduces the interference of noise on the signal and realizes the amplification and acquisition of weak signals.(3)In terms of performance testing and signal processing of the unit lead-salt infrared photodetector,this study designed a unit photodetector signal processing system with the microcontroller STC89C52 as the core,using AD15 and Keil software.Based on this system,the performance of the unit lead salt infrared photodetector developed in this paper is tested and evaluated.During testing,an infrared light source with a wavelength of 1550 nm and an optical power of 10 m W was used to irradiate the detector with a chopping frequency of 1 Hz.The study finds that the voltage signal of the 2 mm × 2 mm Pb S detector is 29.802 m V,and its responsivity is 37.440 V/W.Similarly,the voltage signal of the 2 mm × 2 mm Pb Se detector is 4.505 m V,and its responsivity is 5.659 V/W.(4)In terms of performance testing and signal processing of the 8-element facearray lead-salt infrared photodetector,this study designed an 8-element face-array photodetector signal processing system using STM32F103 chip as the core.Based on this system,the performance of the 8-element face-array lead-salt infrared photodetector developed in this paper is tested and evaluated.In the experiments,an infrared light source with a wavelength of 1550 nm and an optical power of 10 m W was used to irradiate the detector with a chopping frequency of 1 Hz.Then,the voltage signals of 8 elements were measured and the corresponding responsivities Rv were calculated.Due to the influence of factors such as chip preparation process,there are slight differences in the signals on the final 8 pixels collected.However,in order for the detector to characterize the difference in different light intensities,the acquired signals need to be corrected.In this paper,the signal values of the eight pixels are corrected to4.06 m V by means of averaging,and the corrected responsivity is calculated to be 5.10V/W.The experimental results show that the lead salt infrared photoelectric detector with some excellent performance is prepared in this paper,and the designed signal processing system can effectively process the signal of the produced detectors.It is found that the detector responsiveness decreases as the optical power increases.Finally,this paper provides a certain basis for the subsequent research of signal processing circuits of photodetectors with higher pixels.