Abstract
The Visible and Infrared Multispectral Imager (VIMI) is one of the main payloads of the GF-5 satellite. It has 12 spectral bands covering the wavelength from visible light to thermal infrared. The imager designed life is 8 years. In order to monitor and correct the radiometric performance of the imager for a long time and meet the user’s demand for the quantitative remote sensing application, the expandable diffuser used for calibration in full FOV and full optical path method is designed. The solar diffuser is installed on the front side of the optical system and does not affect the normal imaging of VIMI. When VIMI need calibration, the diffuser is expand to the front of optical system via the driving mechanism. According to the characteristics of the GF-5 satellite orbit, the requirement of the calibration energy and the installation matrix of the imager relative to the satellite, the expansion angle of the diffuser is 39 degrees. The 430 mm × 430 mm large-size PTEE diffuser is manufactured to ensure full FOV and full optical path calibration. The diffuser’s directional hemispherical reflectance is higher than 95% from 420 nm to 2400 nm and variation of BRDF in the direction of imager observation is better than 2.5%. The diffuser stability monitoring radiometer is designed to monitor the on-orbit attenuation performance of the diffuser. Results of ground simulation experiments and preliminary on-board calibration experiments were introduced.
Highlights
Wang DOIAccording to the characteristics of Visible and Infrared Multispectral Imager (VIMI), such as multi-band, high resolution (large aperture of optical system), long life and high calibration accuracy, we have investigated high quantification payloads such as MTI [1] [2], MODIS [3] [4], VIIRS [5] [6] and OLI [7] [8] and designed a large-scale solar diffuser(SD) and solar diffuses stability monitor (SDSM) to fulfill all optical path and all field of view or-orbit radiation calibration
GF-5 is a high-spectral satellite of China’s high-resolution earth observation system
According to the characteristics of Visible and Infrared Multispectral Imager (VIMI), such as multi-band, high resolution, long life and high calibration accuracy, we have investigated high quantification payloads such as MTI [1] [2], MODIS [3] [4], VIIRS [5] [6] and OLI [7] [8] and designed a large-scale solar diffuser(SD) and solar diffuses stability monitor (SDSM) to fulfill all optical path and all field of view or-orbit radiation calibration
Summary
According to the characteristics of VIMI, such as multi-band, high resolution (large aperture of optical system), long life and high calibration accuracy, we have investigated high quantification payloads such as MTI [1] [2], MODIS [3] [4], VIIRS [5] [6] and OLI [7] [8] and designed a large-scale solar diffuser(SD) and solar diffuses stability monitor (SDSM) to fulfill all optical path and all field of view or-orbit radiation calibration. Part II briefly introduces the on-board calibration instrument. Part IV presents the preliminary on-board calibration performance and results
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