The Subaru Coronagraphic Extreme Adaptive Optics System: Enabling High-Contrast Imaging on Solar-System Scales

Abstract

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a multipurpose highcontrast imaging platform designed for the discovery and detailed characterization of exoplanetary systems and serves as a testbed for high-contrast imaging technologies for ELTs. It is a multi-band instrument which makes use of light from 600 to 2500 nm allowing for coronagraphic direct exoplanet imaging of the inner 3 λ/D from the stellar host. Wavefront sensing and control are key to the operation of SCExAO. A partial correction of low-order modes is provided by Subaru's facility adaptive optics system with the final correction, including high-order modes, implemented downstream by a combination of a visible pyramid wavefront sensor and a 2000-element deformable mirror. The well corrected NIR (y-K bands) wavefronts can then be injected into any of the available coronagraphs, including but not limited to the phase induced amplitude apodization and the vector vortex coronagraphs, both of which offer an inner working angle as low as 1 λ/D. Non-common path, loworder aberrations are sensed with a coronagraphic low-order wavefront sensor in the infrared (IR). Low noise, high frame rate, NIR detectors allow for active speckle nulling and coherent differential imaging, while the HAWAII 2RG detector in the HiCIAO imager and/or the CHARIS integral field spectrograph (from mid 2016) can take deeper exposures and/or perform angular, spectral and polarimetric differential imaging. Science in the visible is provided by two interferometric modules: VAMPIRES and FIRST, which enable sub-diffraction limited imaging in the visible region with polarimetric and spectroscopic capabilities respectively. We describe the instrument in detail and present preliminary results both on-sky and in the laboratory.

The path to visible extreme adaptive optics with MagAO-2K and MagAO-X

“…Our team has considerable experience working with MEMS DMs. [42][43][44][45] Based on lessons learned at SCExAO, 46 the DM will be operated under partial vacuum to achieve a 10 kHz response time.…”

Efficiently feeding single-mode fiber photonic spectrographs with an extreme adaptive optics system: on-sky characterization and preliminary spectroscopy

“…A complete description of the instrument is offered elsewhere. 10 Here we focus on the main elements relevant to this work. The main instrument consists of two optical benches mounted on top of each other connected via a periscope.…”

Implementing focal-plane phase masks optimized for real telescope apertures with SLM-based digital adaptive coronagraphy

“…Further, this has to be combined with advanced observing strategies like Angular Differential Imaging (ADI, see [6]) to enable PSF residuals subtraction, achieved through state-of-the art data reduction algorithm like LOCI [7] or PCA/KLIP [8]. High-contrast "planet imager" instruments meeting all these requirements have only been recently commissioned on 8+-m class telescopes [9][10][11], and are starting to deliver impressive first science [12,13]. In the foreseeable future, better contrast will only be achievable from space observatories, e.g.…”