Opto-mechanical System Design and Field Experimental Analysis of Hyperspectral Ratio Radiometer

Aiming at the technical requirements of high-frequency and high-precision calibration of optical remote sensing satellites in China, and the current shortage of manual calibration, a hyperspectral ratio radiometer system was developed. The instrument has long-term automatic observation function with a spectral range of 400~2500 nm. The optomechanical system consists mainly of a front optical system and a spectral module. According to the parameter requirements in the site calibration and the target of automatic calibration, the instrument designs the integrating sphere to measure the total irradiance, and realizes the measurement of the diffuse irradiance by occlusion, and obtains the diffuse ratio data in the satellite calibration. Designing optical lenses to achieve ground radiance measurements for automatic observation of atmospheric-surface radiation characteristics. At the same time, the instrument integrates real-time pre-processing and remote transmission of calibration data. In order to verify the field environment adaptability of the instrument and the reliability of the automated measurement data, an external field comparison experiment was conducted with the traditional method of manually measuring the surface reflectance and the diffuse ratio. The experimental results show that the relative deviations of the total irradiance, diffuse irradiance and direct irradiance measured by the two methods are less than 5%, and the absolute deviation of the diffuse total ratio is less than 0.025%; the overall trend of the measured reflectivity the same, and the deviation of the two is generally within ±1%, the maximum deviation is less than ± 2.5%. The hyperspectral ratio radiometer has high automatic measurement accuracy, can replace the artificial measurement of atmospheric radiation characteristic parameters and surface reflectance, and achieve higher measurement frequency. It has broad prospects in the field of remote sensing satellite automatic calibration.