Research Of Key Technologies And Application For High Sensitivity Short Wave Infrared Imaging

Spectral imagery is an important field observation technology,as its high-resolution spectral images play an important role in the national economic construction and scientific research.With the improvement of the spatial resolution and spectral resolution,high sensitivity information acquisition technology has become a key technology of high resolution hyperspectral imager.In this paper,the key technology of SWIR high sensitivity imaging,the application of room temperature thermal imaging,and the hyperspectral imaging are deeply researched based on the domestic HgCdTe SWIR FPA.The main contents and innovations include:1)Theoretical analysis of the generation mechanism of time domain and airspace noise is provided.Based on the improved system SNR model,the method of improving system SNR is proposed.A low noise and high speed information acquisition system is established by using the electronic noise reduction methods.Such as detector matching amplifier,low noise bias and design of reducing the system bandwidth,and the methods have been simulated and experimentally tested.The total background noise of the information acquisition system is less than 231e~-,where the circuit noise is less than 10e~-,under the condition of 10MHz sampling frequency,100Hz frame rate and 10ms integral time.2)The conceiving of high sensitivity short wave infrared system for thermal imaging for room temperature target is proposed,and the research and experimental verification are carried out.The noise equivalent temperature difference(NETD)of SWIR,MWIR and TIR broad spectrum gaze imaging systems were calculated and compared respectively.The results show that the high sensitivity SWIR imaging system has the advantage of thermal imaging in the small temperature range,and shows the potential of SWIR thermal imaging.The requirements for SWIR imagery to obtain NETD better than 100mK in thermal imaging are analyzed in the paper,which including system cut-off wavelength,dark current and detector readout noise.The thermal imaging of SWIR was carried out in the laboratory.At the temperature of 310K of the blackbody,the NETD of the system reached 24mK.The thermal imaging for room temperature target by using high sensitivity SWIR was realized for the first time.3)The limited dynamic range of SWIR imaging system resulting difficulty in detection of complex and radiated large scene with high sensitivity.In order to solve the dilemma,a method to obtain large dynamic range image based on the Multiple readouts per integration period(IMRO)working mode is proposed.This method extends the dynamic range of SWIR system by multi-exposure time image fusion,and realizes simultaneous detection of strong target and weak target.Owing to the method,the dynamic range of the SWIR system is extend from 70.5dB to 90.6dB,and a new acquisition of large dynamic range of low light image is realized.4)The low noise detection system developed in the paper was applied on the airborne SWIR hyperspectral imager with 3nm spectral bandwidth.The single mode of SWIR system was built and based on which hyperspectral imaging is realized.After the integration with ultraviolet,VNIR and TIR modules,the flight test was carried out.Hyperspectral image with 1.5m ground resolution was obtained,the image has achieved the desired results.