Research On Noise Suppression Technology Of Uncooled Infrared Detector

As an important member of infrared imaging technology,uncooled infrared detectors(UIFPA)have a very broad market in the military and civilian areas.Compared with the refrigeration type infrared detector,it has many advantages such as low cost and power consumption,small size,reliable performance and so on.With the development of uncooled detector technology,it is likely to gradually replace the refrigeration infrared detector in the high-end,mid-range and low-end infrared imaging market.So it is the mainstream of infrared detection technology development in the future.At present,uncooled infrared detectors still have the problem of relatively large noise and low response rate.As a matter of fact,the infrared imaging technology in our country falls behind the developed countries.Based on a domestic M01 AB type uncooled infrared detector chip,we designed a set of low-noise uncooled infrared imaging system and study the technologies of random noise suppression and nonuniformity correction.The main works of this dissertation are summarized as follows:(1)The development of uncooled infrared detectors,application value and basic theory of infrared radiation were introduced.And the characteristics of micro-bolometer,noise type,readout circuit structure,etc were explored in detail.(2)A low noise imaging circuit system(including Schematic and PCB)was designed.Low noise fixed bias and high precision adjustable bias module,low noise signal conditioning module,high precision ADC sampling quantization,temperature control module,gigabit network interface module were introduced.(3)Using FPGA as the core,Verilog HDL for the programming language of the entire logic circui,the precise drive control and digital transmission function were realized.The method of 2D-TDI based on hardware was used to suppress random noise,and achieved good results.(4)The definition of nonuniformity and the nonuniform origin of uncooled infrared detectors,and the commonly used nonuniformity correction methods were demonstrated in detail.Conducting the nonuniformity correction using the two-point method for this image of the system.(5)The circuit structure model of the microbolometer and its related bias and signal output characteristics were studied.A new method of on-chip real-time non-uniformity correction based on detector-sensitive bias is proposed and implemented.Compared with the commonly used method of signal post-processing,this method greatly improves the nonuniformity of the detector's original signal and reduces the original signal non-uniformity from 1.9% to 0.4%.