SCExAO Visible Mode: Diffraction Limited Images on a 8 Meter Telescope

Friday, 25 January 2013 9 a.m. — 10 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
Vincent Garrel (Subaru Telescope, AO-Fellow Candidate & Gemini South Visiting Astronomer)

Development of Adaptive Optics (AO) systems allows large ground-based telescopes to restore their theoretical angular resolution, degraded by the optical aberrations induced by atmospheric turbulence. Such systems now routinely deliver diffraction-limited images in the near-infrared domain but still lack the accuracy necessary to a valuable correction in shorter wavelength domains.  Despite its smaller diameter, the Hubble Space Telescope still demonstrates a higher angular resolution in the visible domain and repeatedly demonstrated the scientific interest of such capacity.

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system, currently under development, is an instrument optimized for high contrast imaging of exoplanets and disks on the Subaru Telescope. In parallel of the near-infrared observations, it will also offer near diffraction limited imaging in the red band. This channel is a dual band imager based on two high-speed, high efficiency, low readout noise detectors running synchronously. It uses an hybrid technique based on the correction of the current AO188 system combined with a variant of the short exposure images selection technique (Lucky Imaging).

I will describe the current development of this new instrument. I will also present an original algorithm that greatly improves the Lucky Imaging efficiency, using selected information in the Fourier plane instead of the image plane. I will finally present the promising results of this new instrument, using data taken during its first observing nights.