Illumination system in visible light with variable solar-divergence for the solar orbiter METIS coronagraph

Abstract

The measurement of the stray-rejection capabilities of METIS is part of the acceptance package of the instrument. The Illumination System in Visible Light (ISVL) has been developed to allow the stray-light rejection measurement down to 1x10<SUP>-9</SUP> and under different operating conditions. The main characteristics of ISVL are outlined and discussed; the activities for the integration and verification of ISVL included the absolute radiometric characterization of the facility, including radiance measurement and radiance spatial and angular distribution. The procedures used to measure the performances of the facility are discussed and the obtained results illustrated.