Critical Studies On Digital Domain Time-Delay-Integration(TDI) Infrared Detection System

Infrared digital domain time delay integration(TDI)detector is a new type of detector in recent years.The detector is based on the third generation infrared focal plane detector,the signal generated by the detector photosensitive element through the analog-to-digital conversion,and then the time delay accumulation,by increasing the exposure time to effectively improve the infrared target detection sensitivity The Infrared detection system with digital domain time delay integral technology is more flexible and has very important application in weak space-based target detection.As the infrared digital domain TDI detection using digital domain time delay integration technology,so that in the system design and information processing and many other aspects and the traditional infrared TDI detection are significantly different.In this paper,the research on the characteristics of digital domain TDI detector and the key technology research of weak target detection are carried out.The infrared digital domain TDI detection experiment system is built with domestic 640 × 8TDI detector as the core of infrared digital domain,which verifies that the theoretical analysis is correct and the detection methods are feasible.This paper introduces the research at home and abroad and space application status of infrared TDI detector,and establishes the mathematical model of TDI weak target detection in infrared digital domain.The paper analyzes the influence of heterogeneity,blind-pixel and velocity mismatch on the detection of weak target in detail.The paper focuses on the blind-pixel detection and compensation method of TDI detector and the heterogeneity correction technique.The paper focuses on the problem of velocity mismatch in the infrared digital domain TDI weak target detection,and a method of detecting the velocity mismatch rate is proposed,and discusses the possibility of realizing weak and small infrared target detection in the presence of velocity mismatch.Based on the theoretical analysis,the relationship between the signal-to-noise ratio improvement and the integral series in the digital domain TDI imaging system is obtained,and a method of inter-frame interleaving compensation for the blind-pixel compensation of the detector is proposed.In this paper,the velocity mismatch model and the oversampling model of the digital domain TDI detector are established.The essence of the velocity mismatch is pointed out.The limit condition of the velocity mismatch is given.Aiming at the global exposure TDI detector,the concept of calculating TDI is proposed according to the inter-frame imaging relationship and velocity mismatch.The paper gives the experimental results of digital domain TDI system.The main innovations are as follows:(1)In the process of blind-pixel detection,the blind-pixel detection of the detectionsystem is carried out by the method of row detection and column detectionindependently.In the process of blind-pixel compensation,using the scanningimaging characteristics of the detection system,blind-pixel gets realcorrespondence in an instant field of view by using inter-frame interleavedcompensation(2)A method of velocity mismatch detection based on inter-frame matching ispresented,and the velocity mismatch rate can be obtained by using this detectionmethod.By setting the appropriate digital domain TDI integral series,we canachieve a certain velocity mismatch under the case of weak target detection.Theresults of this paper have important theoretical significance for infrared digitaldomain TDI detector and its application in infrared high-resolution imaging andspace-based weak target detection system.