HARMONI at ELT: towards final designs and AIT strategies for SCAOS sub-system in NGSS

HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 470nm to 2450nm with resolving powers from 3300 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes, SCAO (including a High Contrast capability) and LTAO, or with NOAO. The project is preparing for final design reviews. We present the opto-mechanical designs of the SCAOS sub-system for single-conjugate adaptive optics, which is one of the AO sensors of the NGSS system (natural guide stars sensors) of the HARMONI instrument, and the AIT strategies at LAM. SCAOS will measure the turbulent wavefront and will control the ELT M4/M5 mirrors for the SCAO mode. This sub-system is based on a pyramid wavefront sensor and uses multiple optimizations as optical optimization loop, pupil stabilization loop, low-order loop, object selection, ADC and K-mirror. We present the almost final opto-mechanical designs and the AIT strategies for the SCAOS sub-system.