Research On Improving The Accuracy Of Ground-based Infrared Radiation Characteristics Measurement System Based On Blackbody Calibration

The rapid development of the infrared detector manufacturing industry has greatly promoted the application of infrared imaging technology,and the infrared radiation characteristics measurement technology developed on this basis,unlike the traditional image feature recognition technology,provides information on the shape and outline of the target object,but also provides information on the radiance,radiant intensity and other characteristics of the target,which helps to achieve early warning identification of targets,detection and performance of related equipment Evaluation.Due to the increasing complexity of the range measurement test conditions and the high-speed dynamics and diversity of the measured targets,which increase the difficulty of military target tracking and measurement tasks,ground-based range infrared radiation characteristics measurement systems are widely used in the military field by countries for their outstanding advantages in target detection.With the improvement of military power of each country,various kinds of high precision weapons are emerging,and in order to meet the challenges of more accurate measurement of various military targets and better evaluation of weapon performance,the measurement stability and measurement accuracy of ground-based infrared radiation characteristics measurement systems have also put forward higher requirements.From the perspective of infrared radiation characteristics measurement principle,the system infrared radiation characteristics measurement accuracy is affected by many factors,including the system calibration error,the system operating environment temperature changes and detector non-uniformity and other factors.Based on the theory of infrared radiation characteristics measurement,this dissertation presents the equivalent calibration method of large-size surface source blackbody,the fast compensation method of system temperature drift based on blackbody calibration,and the wide dynamic non-uniformity correction algorithm based on blackbody calibration,based on the in-depth study of existing blackbody radiation calibration methods,to improve the working stability and measurement accuracy of ground-based infrared radiation characteristics measurement system.The purpose of this thesis is to improve the stability and accuracy of the ground-based infrared radiation measurement system.The main research work accomplished in this dissertation is as follows.(1)In-depth study of the principle of infrared radiation characteristics measurement,analysis of the transmission and transformation process of target radiation in infrared imaging systems,detailed derivation of the blackbody radiation calibration model of the system based on the response characteristics of the infrared radiation characteristics measurement system,establishment of a linear response relationship model between the input of target radiation and the grayscale output of the system,to provide theoretical support for improving the measurement accuracy of the system based on the blackbody radiation calibration technology.(2)The advantages and disadvantages of short-range spread source calibration and direct imaging calibration are analyzed and compared.Based on the near-extendedstandard-source calibration method,an equivalent alternative method of large-size area source blackbody calibration is proposed to solve the problems of long heating time and low efficiency caused by large-size area source blackbody calibration in largeaperture ground-based infrared radiation characteristic measurement system,which simplifies the calibration work of large-aperture infrared radiation characteristic measurement system in the field and improves the efficiency of radiation calibration without affecting the calibration accuracy.(3)Briefly analyze the composition and transmission process of stray radiation inside the infrared system,understand the sources of temperature drift in the infrared system,and analyze the influence of temperature drift on the response parameters of radiation calibration.The analysis summarizes the temperature drift compensation model based on detector calibration and two ambient temperature calibrations,and proposes a system temperature drift fast compensation method based on the radiation calibration equation considering ambient temperature,using 4 calibration images to solve the temperature drift coefficient,which greatly improves the efficiency of temperature drift compensation,maintains the stability of radiation calibration,reduces the deviation of gray value caused by temperature drift,and effectively improves the measurement accuracy of infrared radiation system.(4)Briefly introduce the sources of non-uniformity of infrared focal plane array(FPA)detectors and analyze their effects on radiation measurement accuracy.The calibration-based non-uniformity correction method(NUC)is introduced in detail,and a non-uniformity correction improvement algorithm based on two-point calibration with single-point compensation is proposed,and the integration time is considered on top of this to improve the dynamic range of NUC,and finally the detector is more accurately corrected by NUC with multi-scale area decomposition to improve the NUC effect and further reduce the image non-uniformity,improves the measurement accuracy of infrared radiation system.This dissertation is based on the response model of the ground-based infrared radiation characteristics measurement system and the detailed analysis of the blackbody radiation calibration technology principle and a large number of experimental measurements to demonstrate the effectiveness of the proposed method.In the largeaperture surface-source blackbody equivalent calibration method,the maximum error between the calibration method based on the calibration equivalent conversion model and the large-aperture surface-source blackbody direct calibration method is less than1%,which effectively simplifies the calibration of the external field large-aperture infrared characteristic measurement system without affecting the calibration accuracy.The fast temperature drift compensation method based on blackbody radiation calibration uses 4 calibration images for fast and effective temperature drift compensation,and the average error of gray scale after compensation is reduced from1.02% to 0.42%.The wide dynamic range non-uniformity correction technique based on multi-scale area decomposition combined with two-point calibration and singlepoint compensation further reduces the non-uniformity of detector,and the average non-uniformity at each integration time decreases from 0.16%,0.16%,and 0.50% to0.08%,0.07%,and 0.18%,respectively,and the linear interpolation of correction coefficients considering the integration time on this basis improves the dynamic range of NUC,and finally,the grayscale response of the detector image element is effectively improved by multi-scale area decomposition,and the correction range can be flexibly selected according to the target imaging area as well as the size of imaging area.