Research On Portable Shortwave Infrared Low Light Imaging And Image Enhancement Technology

Short-wave infrared has important application value in remote sensing,military,industrial,agricultural,medical and other fields because of its unique wavelength attribute.Especially in moonless nighttime,short-wave infrared is the band with the highest radiance in the gas-emitting spectrum,so short-wave infrared imaging has become one of the technical directions of the new generation of low-light night vision equipment.Among the commonly used detectors in short-wave infrared photoelectric systems,InGaAs detector has the advantages of high detection efficiency,no need for low-temperature refrigeration,small size,low power consumption,etc.,and the market share of it is increasing year by year,but the performance level of InGaAs detectors in our country still lags behind that of foreign countries.In order to promote the technological progress of domestic InGaAs detectors,this thesis has developed a portable low-light-level night vision imaging system based on the InGaAs short-wave infrared detector independently developed by Shanghai Institute of Technical Physics,Chinese Academy of Sciences.And aiming at the characteristics of short-wave infrared image,the enhancement algorithm of low-light image has been deeply studied.The main tasks completed in this thesis are:(1)Through the analysis of characteristics and technical parameters of the domestic 320×256 InGaAs short-wave infrared detector,the overall design of the imaging system was completed,and the time noise and spatial noise of the system were analyzed,which provided theoretical guidance for low-noise electronics design;(2)With low noise and low power as the design principle,the electronic design of imaging system based on FPGA was completed,including the design and development of power management module,detector driver and analog-to-digital conversion circuit,image preprocessing module,USB communication and PAL video coding circuit,etc.;(3)Aiming at the low contrast imaging under low illumination condition,which limits short-wave infrared camera's optimal night vision performance,a short-wave infrared low-light image enhancement algorithm based on wavelet transform and pairwise target contrast was proposed.Comparing the enhancement effect of the proposed algorithm with other algorithms,the results showed that the proposed algorithm had a certain performance improvement in the enhancement of short-wave infrared low-light image;(4)The signal-to-noise ratio(SNR)and power consumption of the system prototype were tested,and the imaging experiments were carried out in hazy days and moonless nights.The results showed that the system scheme and the electronic design were reasonable and met the expected design targets.