Research On Driving And Information Acquisition Technology Of The Infrared Cooled Detector

Infrared detectors have been developed for more than 200 years,from the first generation with unit devices to the fourth generation with high performance,high resolution and large area array.According to refrigeration requirements,there are cooled photonic detectors with focal plane and uncooled infrared detectors utilizing radiation heat effects.Infrared detectors are widely used in medical,transportation,agriculture,forestry and aerospace fields,and the long-wave infrared hyperspectral imaging system based on the cooled infrared detector plays an irreplaceable role in geological exploration and atmospheric detection.In this thesis,the cooled infrared detector for long-wave infrared hyperspectral imaging system was studied.Firstly,the noise components of the infrared detector were deeply studied and analyzed based on the principle of the infrared detector.Secondly,a low noise driving and information acquisition circuit system was designed.On this basis,low-pass filtering and multisampling averaging combined with multi-frame superposition methods were used to denoise the system.Finally,MTF and NETD of the whole system are tested by longwave infrared hyperspectral imager to verify the performance of the system.The main content and the research findings are listed below:(1)A driver and information acquisition circuit is developed based on MARS VLW LS5 which is a cooled infrared detector produced by Sofradir.The overall structure and function of the circuit,the selection of the chip and the design of PCB are elaborated respectively,and the noise of signal preprocessing circuit is also analyzed.Design and Simulation of driver timing of detector and serial-parallel conversion timing of A/DC data transmission are based on FPGA.(2)Based on the principle of the photoconductive infrared detector used in this subject,the noise components of the infrared detector are classified and analyzed theoretically,which lays a theoretical foundation for the subsequent noise reduction processing of the thesis.(3)As for the white noise components in the system,we use A/DC multiple sampling and multi-frame superposition to reduce noise.We analyze A/DC multiple sampling combined with selection of filter bandwidth,then determine the bandwidth and sampling point location based on simulation waveform.Next,we use FPGA combined with external SRAM to process and transmit data after multiple sampling averaging.Finally,we select 8 sampling averaging and 4 frame superposition,according to the analysis of the experimental data.SNR and NETD are improved evidently.MTF and NETD were tested in the long-wave infrared hyperspectral imaging system,The MTF of the system is about 0.363,and the average NETD of all bands is less than 0.2K.