METIS first light imager and spectrograph for the ELT: Overview of the near and mid-infrared detector subsystems

The METIS instrument (Mid-infrared ELT Imager and Spectrograph) is one of the three first-light instruments for the ELT.(1,2) It will work in the mid-infrared with a set of four different focal planes, grouped in three different subsystems: the imager (IMG) and the spectrograph (LMS) are the two scientific focal planes, and the last one, SCAO, is the dedicated adaptive optics system. In total, this instrument requires five H2RG detectors (5.3 mu m cutoff), one SAPHIRA detector (2.5 mu m) and one GEOSNAP (13.5 mu m). All of these detectors will be controlled by the New General Controller, second generation (NGCII). These three separate subsystems require specific tests and development : the IMG needs a fast readout for both N and LM channels, the LMS requires a mosaic of four detectors and SCAO works with one single detector operated fast for AO corrections. In this paper, we will present the challenges for the development of the detector systems of the three detector subunits in METIS. This includes the design, tests and preparations for the AIT/AIV phases that each subsystem has to go through. First, we describe the detector-specifics of all the instruments. In a second part, we go over the design challenges for these detector subunits. In the end, we will report on the current testing.