On-orbit Radiometric Calibration Method For Gaze Camera With Large Planar Array

Space remote sensing has widely used in many fields,such as national economic construction and national security.At present,optical remote sensors are developing with high spatial,spectral and temporal resolution.Meanwhile,the accuracies of radiation calibration and geometric location are also required to improve.Highprecision radiometric calibration directly determines the quantitative application capability of the remote sensing instruments,as well as the application range and practical value of the obtained data.The remote sensing camera is subjected to strict calibration and testing by the laboratory before launching.However,during the launching and on-orbit operation,on-orbit correction is still needed due to the changes of environments around the instruments and its own characteristics.Since the space remote sensing cameras with diameter over 400 mm cannot use all-optical radiation calibration,this dissertation proposes a radiometric calibration method for infrared gaze camera with large diameter combining the inner blackbody and infrared reference stars.The main research contents and innovations include the following four aspects:1.As the existing radiation calibration equipment and method have defects and deficiencies in the on-orbit radiation calibration of the planar array gaze camera system,this dissertation presents an on-orbit radiation calibration method combining the blackbody and the stars and builds a cross-corrected radiation calibration model,with an absolute radiation calibration accuracy better than 9%.2.To solve the influence of the accuracy of intra-pixel response function of star energy extraction in high energy-concentration infrared detection system,this dissertation establishes an cross-pixel imaging model of infrared camera and proposes a method using template to solve spatial distribution of intra-pixel response function,which calculates the star centroid coordinates and the response of the intra-pixel based on observing data of 6~7 magnitude stars.The experimental verification reduces the target energy extraction accuracy from 30% to 4.9%.3.An improved two-dimensional Lagrange's interpolation is proposed to correct the image distortion with a better precision than 0.36 pixels,overcoming the shortcomings of the traditional method in correcting non-radial distortion images.4.This dissertation also proposes a model using the multi-catalogue data to extrapolate the energy of specific band,which can be converted into an arbitrary band of camera,through the cross-validation of observation data based on WISE,IRAS and 2MASS catalogue and the accuracy of energy extrapolation is higher than 3%.Moreover,combined with the adaptive segmentation of radiation correction in pixel level of blackbody,this dissertation selects 6~7 magnitude stars with extrapolation accuracy less than 1% as the calibration to test the in-orbit calibration,achieving a comprehensive precision of 9%.Compared with the global traditional calibration methods,the calibration project in this dissertation uses the full optical path radiation calibration of the large diameter gaze infrared detection instruments,which provides the theoretical and experimental reference for on-orbit radiation calibration of the large planar array space remote sensing cameras.