Laboratory Full Field Of View Polarization Calibration Of Directional Polarimetric Camera

Polarization imaging technology has become a hot spot in the field of optical detection,show a wide application prospect and value in the respects of target detection,biomedical diagnostics,astronomical observation,atmospheric remote sensing.Systematic errors of polarimetric instrument commonly exists,which affect the detecting accuracy.In order to ensure that their performance will meet the requirements on polarimetric accuracy and minimize the instrumental systematic errors,the specific calibration which is different with the individual instrument is usually performed.The Directional Polarimetric Camera is a kind of ultra wide view of spaceborne remote sensor,which Polarimetric accuracy is of great significance in the inversion of physical properties of the atmospheric aerosol and cloud,and the laboratory polarization calibration of the instrument is a important research subject.In this paper,starting from the mathematical description tool of polarization called Stokes-Mueller matrix,combining with the features of Directional Polarimetric Camera optical system,the instrumental radiation measurement model including the polarization effects is derived in detail.Considering the principle and feasibility of the calibration,the relative difference of full field of view radiometric response is divided into two parts called low-frequency transmission variation and high-frequency variation,and the polarization effect of the wide-view lens is inducted into a comprehensive optic polarization rate parameter in the model.The instrumental imaging response results of the full-field of view in two cases that the incident light are non-polarized and complete line polarized are simulated,making a macroscopic understanding about the imaging characteristics of the instrument.The measurement error of polarization degree caused by the calibration deviations of instrumental principal parameters are analyzed and calculated.Meanwhile,according the error analysis results,the preliminary individual instrumental parameters calibration tolerance allocation is researched.These studies have provided theoretical basis and experimental guidance for the specific calibration of Directional Polarimetric Camera.The calibration methods,calibration experiments and analysis evaluations are researched.The rationality of a comprehensive optic polarization rate parameter represented the polarization effect of the lens in the measurement simplified model is verified by the specific experiment.The general principles and framework of full field of view polarization calibration of the instrument are introduced.The calibration methods of the principal instrumental parameters in the model is designed and the specific calibration experiments is carried out,such as the relative transmission of the polarized channels,the high frequency part of the spatial variation mainly due to the inter-pixel sensitivity variation,the low frequency variation part of the spatial relative transmittance mainly due to the lens,the optic polarization rate of the lens,the absolute orientation of the polarizer in wheel.The calibration of all instrumental parameters in the measurement model is basically completed.Finally,in order to fully guarantee the measuring accuracy of the instrument,the performance measurement and correction about some factors out of the instrumental measurement model are carried out.The mechanism of the artefacts smear of the frame-transfer CCD is analyzed,and two kinds of frame transfer correction algorithms are introduced.The correction algorithms using the optical black region is recommended according to the experimental comparison results.The radiation dynamic range of the instrument is calculated by adjusting linearly the spectral radiacne of the light source.The demand of the multi-polarization co-registration due to the optical wedge is analyzed according to the actual application situation,and the actually registration values is calibrated by the experiment.The controllable polarization light source system in our lab is introduced in detail,and the instrumental detection accuracy verification experiment is carried out by using the light source system in several typical field of view.Furthermore,the full field of view polarization measurement accuracy of the instrument is verified by using large integrating sphere non-polarized light source.The detection accuracy of the Directional Polarimetric Camera is ensured,the demand of the application data inversion is meet,and the systematic resources of laboratory polarizaiton calibration of the instrument is provided by this research.