HARMONI at ELT: development of the high-contrast module

HARMONI is the first light near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics (AO) modes - Single Conjugated AO ( SCAO - including a High-Contrast capability) and Laser Tomography AO (LTAO) - or without AO (NOAO). The project is preparing for Final Design Reviews. In addition of the SCAO mode, the instrument includes a high-contrast imaging capability working in H and K band. This sub-system will be essential to spectrally characterize young giant exoplanets with contrast down to 1e-6 and a separation from 0.1 to 0.3 arc second (goal: 0.05-0.3 '') from their host star. It will also be used to characterize young circumstellar disks. The High-Contrast Module (HCM) is based on an apodized pupil coronagraph which lowers the intensity of the diffracted starlight to a planet-star contrast compatible with the dynamic range of the scientific detector. A dedicated Zernike wavefront sensor will internally calibrate non-common path aberrations at a 0.1Hz rate. This paper therefore recalls the driver requirements before describing the optical, mechanical and control system designs. We then shortly describe the operation of the HCM. Section 3 addresses the main aspects of the system analysis while the last section is dedicated to the AIT aspects.