Radiometric model of a hyperspectral instrument for Earth observation

Abstract

In the near future, it is expected to have an increased number of satellites with hyperspectral imager instruments in orbit. Consequently, in the context of an internship and a Master’s thesis performed in Liège Space Center (CSL-Acronym in French) it has been proposed to model a hyperspectral instrument for Earth observation (HIEO). Indeed, a few models of hyperspectral devices from satellite imaginary have been founded and none of them provides a clear estimation of the photon-electron energy nor its SNR (Signal to Noise ratio) transfer from a standard scene until reaching the detector. In order to reach this objective, three modulus were built; the scene, the optical-mechanical system and the photon-detector. This project aims to build and implement from scratch a radiometric model of a hyperspectral instrument for Earth observation, using key data parameters (KDP) for the scene module, optical module and detector module , in the narrow region VNIR (Visible and Near Infrared domain from 400 nm to 1100 nm).

It was found that the modeled optical-detector system convert a tiny amount of photons into electrons. Furthermore, higher values of SNR (>100) were found in the region between 500 nm to 900 nm. Moreover, the SNR drastically drops towards the extremes of the spectrum. In conclusion, the relation signal noise has a non-linear relation between the grating efficiency, quantum yield and the quantum efficiency. Thus, futures studies could improve the prediction of these parameters to have better data for the correction of hyperspectral radiance profiles.