Pre-Launch calibration of the Vis-IR Hyperspectral Imager (VIHI) onboard BepiColombo, the ESA mission to Mercury

摘要

This paper reports the design, assembly and calibration activities relative to the internal calibration unit mounted on the Visible and Infrared Hyperspectral Imager (VIHI). VIHI is one of the three optical channels of the SIMBIO-SYS suite (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem), one of the payload instruments onboard the probe BepiColombo/MPO, the ESA cornestone mission to be launched in 2016-2017 to Mercury. The activities reported include also the qualification tests of the commercial sources (a Welch-Allyn 1163 incandescence lamp and the NICHIA NJSW036BLT LED) selected. All the qualifications (Thermal, Vibration and Radiation tests) were successful, demonstrating the suitability of the commercial sources as Flight hardware. The performances of the ICU were verified during its mounting and alignment in the VIHI optical bench. The ICU satisfy the requirements of providing a spectral radiance of the same order of magnitude of the signal from Mercury and of guaranteeing a good degree of spatial uniformity across the spectrometer slit for the verification of the flat field in flight. The LED source provide an uniformity of the order of 10%, while the lamp signal drops by about 30% at the extreme edges of the FOV.