Study Of The Important Factors Affecting The Polarimetric Accuracy Of The Multi-channel Polarimeter

The polarimetric accuracy is one of the most important parameters of polarization sensors.And it is also an important focus aspect of the atmospheric parameters retrieval,the remote sensing data application and so on.However,polarization measurement has its unique requirements and complexity compared with the general radiation measurement because of its specialty measurement mode of polarization,which have numerous and interrelated factors.It is necessary to analyze carefully in order to realize accuracy enhancement of the Multi-channel Polarimeter.To achieve very high polarization measurement accuracy,the number of error terms to be taken into consideration is geometrically increased.It is a way to simplify the problem by calibration and the polarization detection matrix of the instrument,and by controlling the tolerance of each unknown parameter in the polarization detection matrix to reduce the error of the final measurement.In this article,it presents its polarization calibration model according to the characteristics of the Multi-channel Polarimeter.And meanwhile,based on the unknown parameters in the polarization measurement matrix,the important factors,which is affecting the polarimetric accuracy of the Multi-channel Polarimeter,are given.Secondly,focusing on how to improve the polarimetric accuracy of the instrument,the important factors,which are affecting the accuracy,are analyzed and discussed.And then the errors budget are obtained.At the same time,for different key factors,different methods are adopted to reduce their influence on instrument polarization measurement accuracy.At the same time,according to the high stability demands of dark current of the short wave infrared detector and operating temperature,the pulse width modulation signal,which is established by FPGA based on the switch control algorithm,control current of the thermoelectric refrigerator.It meets the accuracy stability requirement of operating temperature.Finally,the dark current uniformity test shows that the offset of dark current is controlled at a reasonable level;In addition,the core performance of the filter and the polarizer is analyzed,and the magnitude of the out of band response and the extinction ratio can be ignored?At the end,the way of the instrument polarization calibration is designed,and the laboratory polarization calibration of the instrument is finished.Then,the degree of absolute spectral response measurement,relative transmittance,nonlinear,non stability and multi polarization channel field overlap,and polarizing plate through the relative deviation of axis are tested.The results showed that a polarization measurement accuracy,which meets the requirements in actual applications,is better than 1%when the input degree of polarization was 20%.It indicates that the calibration method and the analysis of the errors budget is effective.