Coronagraphy for DiRect Imaging of Exoplanets (CIDRE) testbed 1: concept, optical set up, and experimental results of adaptive amplitude apodization

Oncoming exoplanet spectro-imagers like the Planetary Camera and Spectrograph (PCS) for the Extremely Large Telescope (ELT) will aim for a new class of exoplanets, including Earth-like planets evolving around M dwarfs i.e., closer than 0.1" with contrasts around 10(-8). This goal can be achieved with coronagraphs to modulate the incident wavefront. However classical coronagraphs are not optimal: 1) they impose a planetary photon loss, which is particularly problematic when the instrument includes a high spectral-resolution spectrograph, 2) some aberrations such as the missing segments of the ELT are dynamic and not compatible with a static coronagraph design, 3) the coupling of the exoplanet image with a fiber for spectroscopy only requires the electric field to be controlled on a small target-dependent region of the detector. Such instruments would benefit from an adaptive tool to modulate the wavefront in both amplitude and phase. We propose to combine in the pupil plane a deformable mirror (DM) to control the phase and a digital micro-mirror device (DMD) i.e., an array made of 1920 x 1080 micro-mirrors able to switch between two positions, to control its amplitude. If the DM is already well-known in the field in particular for adaptive optics applications, the DMD has so far not been fully considered. At IPAG, we are currently assembling a testbed called CIDRE (Coronagraphy for DiRect Imaging of Exoplanets) to develop, test, calibrate, and validate the combination of these two components with a Lyot coronagraph. Since March 2022, CIDRE is assembled albeit without the Lyot coronagraph yet. The first few months have been dedicated to the calibration of the DMD. Since May 2022, it is operational and used to test dynamic amplitude apodization coronagraphs (so-called Shaped Pupils). This proceeding presents the set up of the CIDRE testbench and the first experimental results on adaptive Shaped Pupils obtained with the DMD.