Visible and near infrared detector for BepiColombos spectrometer VIHI

¹ Observatoire de Paris, LESIA/UMR CNRS 8109, 5 place Jules Janssen, 92195 Meudon Cedex, France
² INAF, IASF, via del Fosso del cavaliere, 100, 00133 Roma, Italy
³ Selex Galileo, Space LOB, via Einstein 35, 50013 Campi Bisenzio, Italy
⁴ Raytheon Vision Systems, 75 Coromar Drive, Goleta, California 93117, USA

Corresponding author: yann.hello@obspm.fr

Abstract

VIHI: the Visible and Infrared Hyperspectral Imager is one of the three channels of the Simbio-Sys instrument for the BepiColombo mission to Mercury. Its scientific objective is to study the hermean surfaces composition by sensing the photon flux reflected off the planet. VIHI works in the range of 400 to 2000 nm with a spectral resolution around a few hundreds. The particularity of this channel is the use of a single detector matrix (264 × 264) for both visible and infrared wavelengths. Getting the visible part of the detector responsivity is achieved by thinning an infrared HgCdTe matrix because visible light is completely absorbed inside the substrate. The thinning process is well controlled since a long time and was used to increase number of thermal cycle of the hybrid devices. Recently, this process is able to remove completely the substrate and, thus, open the detector to the visible range. The detector is a custom design made by Raytheon Vision System in Goleta (USA). In this paper, we will describe the expected performances of the detector which is designed to work in the very harsh radiation environment of Mercury.