Technology Study Of Spectrum Ratioing Radiometer Used For Onboard Calibration

The Moderate Resolution Imaging Spectroradiometer,applied to a new generation of ocean color remote sensing,can observe marine coastal zone and the inland lakes with large width,as well as the land atmosphere and cirrus detection.Taking into account the demand of land observation,the dynamic range of remote sensor applied to ocean color observation can not be too small and sensitivity should be larger since the signal intensity of ocean water upward radiation is weak.Radiometric calibration precision of remote sensor was brought forward higher requirements to meet the requirement of ocean color inversion's quantification.It is an effective means applying the Ratioing Radiometer to monitor the change of solar diffuser's reflectance,which is used as light source carrier for on-orbit calibration of optical remote sensor.The absolute radiation on-orbit calibration system,used in the new space-borne High Resolution Imaging Spectrometer(HRIS),has to be designed in order to meet the requirements of quantitative products' inversion.According to the long-term tracking measurement result of foreign on-orbit calibrator,it illustrates that the reflectance of solar diffuser is degrading all the time,and it degrades greater when the wavelength is shorter,while the remote sensing of ocean color element mainly focus on the wavelength region closed to UV.Therefore,it is necessary to develop spectrum ratioing radiometer with high spectral positioning accuracy and high radiation detection sensitivity,which used to monitor the reflectance change of solar diffuser.The article is based on the Moderate Resolution Imaging Spectroradiometer project,aimed to the requirement of onboard calibration scheme and calibration accuracy,spectrum ratioing radiometer is proposed which is used to monitor the reflection performance of solar diffuser.An integrating-sphere used to collect energy and homogenize incident light is designed,which can accomplish to collect the spectral data of different light sources.To realize the spectral continuously monitor of UV VIS NIR spectrum,Beam-splitting elements based on the grating dispersion is introduced.Big pixel CMOS detector is employed to meet the SNR requirement.The main contribution and innovation of the thesis are as follows:1.Scheme design of spectrum ratioing radiometer and the design of electronics system are accomplished;spectrum data collection and data transmission for different of light source are realized,adopting the ground detection device based on the Ethernet;accurate and stable monitoring data is obtained.These provide feasible solution for future onboard calibration circuit of the Moderate Resolution Imaging Spectroradiometer.2.Spectrum orientation of the system is implemented,the test of spectral character and radiation detection performance is accomplished which used integrating sphere as the calibration source,the impact of spectral response function caused by calibration precision of the calibration source is analyzed as well,which provide the design foundation for the further project.3.Simulation testing the change of diffuser's reflect performance is carried out using the prototype,the collected data is processed with different reference standard and corresponding simulated attenuation coefficient of diffusers is obtained,meanwhile,the error of diffuser's area factor is eliminated effectively,which has better value of engineering application.