Research On System-Level Radiometric And Polarized Calibration Methods In Laboratory Of Polarization Remote Sensors

The purpose of system-level radiation and polarization calibration method of polarization remote sensor is to establish and complete the calibration model between polarization response and target radiometric value,to analyze the mechanism of uncertainty factors,to study the methods used for parameter measurement,evaluation,correction and verification of calibration model,and provide calibration data with high precision.System-level radiation and polarization calibration provide basic means of support for the research and quantitative application of the polarization remote sensor,which can achieve the expected radiation and polarization detection precision and being of great significance to improve the quantitative level of polarization remote sensors such as cloud phase state,atmospheric correction and atmospheric aerosol sensors.In this thesis,the polarization response calibration model is established according to the structure composition and detection principle of Channel-type Polarization Remote Sensor and polarization remote sensor with wide field of view,combining with matrix optics and radiation theories.The spectral Mueller matrix and Stokes vector are analyzed for the spaceborne atmospheric corrector,and it is found that the necessary condition for polarization calibration precision to be better than 0.5%is that the relative transmittance between polarized channels and the out-of-band response are both better than 0.4%.Based on the actual measured spectrum transmittance data of light filter and the spectral radiances of different typical targets,the light filter of the atmospheric corrector is screened.The polarization characteristics of EQ99 monochromator light source are studied,and the depolarizer is used to eliminate the polarization.The influence of light source instability is reduced by the synchronous measurement of beam splitter mirror,and the high efficiency and high precision measurement of the relative transmittance between polarized channels is achieved,which provides technical supports for improving the precision of the atmospheric corrector.In order to reduce the effect of detector spontaneous emission on the precision of radiation calibration,high and low temperature environment simulation vacuums are used to measure the thermal radiation response at four temperature points in 2250 nm wave band,and the least square method is also used to fit and correct the spontaneous radiation response,as a result the radiation calibration precision better than 5%under the condition of low dynamic range is achieved.By using variable polarization light source,the system-level precision experiment results of atmospheric corrector show that the precision obtained from 490 to 1610 nm band is better than 0.5%,which confirms the reasonability of Channel-type Polarization Remote Sensor polarization radiation response calibration model.In terms of Directional Polarization Camera(DPC),the methods used for parameter calibrations such as polarization degree and absolute polarization azimuth of polarization remote sensor with wide field of view polarization radiation response calibration model are also studied in this thesis.By using the Fourier series analysis method,the measurement model of the polarization degree of full view is established,and the measurement error introduced by the polarization azimuth absolute position of the reference light source is eliminated,which guarantees the precise measurement of polarization degree.The polarization response of DPC in 865 and 910 nm bands changed with temperature is studied by using high and low temperature environment simulation vacuums,and the polynomial fitting is used to make the correction.For polarization channels,an integrating sphere reference light source with large aperture and sectional viewing field measurement are used to eliminate the influence of the optical wedge plate on the non-consistency of the field view of DPC three partial channel,and high precision measurements of the high and low frequency relative transmittances are achieved.The variable polarization light source and integrating sphere radiation source with large aperture are used for the comparison and precision analysis,and the DPC absolute radiation calibration uncertainty is better than 5%,the DPC relative radiation correction uncertainty is better than 0.5%,the DPC full view polarization calibration uncertainty is better than 0.5%,and the DPC measured polarization degree uncertainty under natural light is better than 0.05%,which confirms the precision and reasonability of polarization remote sensor with wide field of view polarization radiation response calibration model.