Stray-light analysis of Amon-Ra instrument

摘要

The Amon-Ra instrument is the main optical payload of the EARTHSHINE satellite and a unique Earth reflectance monitor. It consists of two separate optical systems, one imaging photon fluxes over the visible waveband and the other bolometrically measuring global emissions while the satellite orbits about the L1-Lagrange point. Two optical systems were designed to share the same apertures to the Sun and Earth and view the same target along the same direction as the spacecraft rotates. This design approach is advantageous in minimising the optics alignment problem as well as the differential degradation of front-end optics and detectors between the two systems. Nevertheless, such an approach makes it difficult to control stray-light separately in each system and the signal of one source may be corrupted due to the other. In this paper, we discuss the stray-light performance of the Amon-Ra instrument and report the analysis results.