Research Of Information Acquisition Key Technologies For High Spatial Resolution Shortwave Infrared

High resolution Shortwave infrared(SWIR)is a promising technology for environment monitoring,fire spot detection,mineral exploration,and camouflage identification because of its fascinating ability in penetrating haze,smoke and night vision imaging.In recent years,high spatial resolution SWIR imaging system has attracted more and more attention with the promotion of application.In this paper,key technologies of SWIR to realize 1m ground sample distance(GSD)in orbit of 500 km are demonstrated and analyzed firstly,the detailed system parameters are also given.The key technologies of SWIR imaging are analyzed comprehensively,the information acquisition technology,which contains of high speed and low noise information collection technology,time delay and digital accumulation technology,and image-based nonuniformity correction,is researched based on InGaAs infrared focal plane array and SWIR imaging system prototype.The principle and mathematical model of these techniques are analyzed theoretically and proved through a number of experiments.The main contents and innovations of the paper include:1)A high resolution SWIR imaging system,which can realize 1m GSD in orbit of 500 km,is designed.The main system parameters are simulated and key techniques are introduced,high speed and low noise information collection technology,time delay and digital accumulation technology,and image-based nonuniformity correction are mainly studied.A prototype of SWIR camera is developed to demonstrate these key technologies and a high speed and low noise information collection system is also designed and integrated.2)Noise types and sources of SWIR imaging system are analyzed from both temporal and spatial dimenstions,the method of improving signal to noise ratio(SNR)is studied on the classical SNR model.Time delay and digital accumulation technology is mainly discussed,and its implementation principle and developments are described.The relationship between the technology and the image SNR and nonuniformity is studied theoretically.For the first time,time delay and digital accumulation technology is applied to large-area SWIR imaging system,and the improvement effect for system SNR and image nonuniformity is demonstrated.3)Image nonuniformity correction is further studied and a new technique combining image statistics and spatial filtering algorithms is proposed.The mathematical model,physical meaning,and applicable conditions of the algorithm are analyzed theoretically.Airborne and spaceborne hyperspectral image data is used to validate the proposed method.The experimental results show that the proposed method not only removes image stripes,but also preserves the image information to an extreme extent.The method can improve image relative radiometric accuracy,and is beneficial to the later quantitative application of image data.4)The designed information collection system is applied to the prototype of SWIR camera,SNR and modulation transfer function are measured.Two imaging experiments,which contain comparison imaging between visible light and SWIR on the condition of haze day and 100?s integration time dizzy imaging are completed.The 100?s integration time is applied to earth observation from space can realize SWIR imaging with 1m GSD in orbit of 500 km.