2kDM dichroic Starbowl

Various SCExAO components: (Left) 2000 actuator deformable mirror (middle) IR/visible dichroic splitter, fixed pupil
mask and delivery fiber for internal calibration source (foreground) (Right) Starbowl wheel.


Applying to use SCExAO ?

See current capabilities for details.
The CHARIS and VAMPIRES instruments are currently available for science use
Additional science modules will be made available once commissionned - check this site for updates


What is SCExAO ?

SCExAO's main goal is to image exoplanets and disks around nearby stars. The SCExAO instrument is permanently installed at the focus of the 8.2m diameter Subaru Telescope atop Maunkea, Hawaii, at 4139m (13,579 ft) elevation.

Light collected by Subaru Telescope is first processed by the AO188 adaptive optics system to remove most of the optical aberrations induced by atmospheric turbulence. The optical beam is then processed by SCExAO, which performs fine wavefront correction (Extreme Adaptive Optics) and removes the bright starlight (coronagraphy) so that exoplanets can be imaged. The beam is then sent to SCExAO's modules and instruments, including CHARIS and VAMPIRES, for imaging, spectroscopy and polarization measurements.

SCExAO as a Science Instrument

SCExAO is an active scientific instrument currently available to astronomers to image and study exopanets and perform other observations requiring high angular resolution.

We provide the following key capabilities:

  • Extreme-AO correction providing high SR in near-IR and diffraction limited imaging in visible light
  • Coronagraphic starlight suppression in near-IR.
  • Near-infrared (0.95-2.4 μm) integral field spectroscopic imaging (R=20-70) with the CHARIS instrument.
  • Near-infrared (0.95-1.7 μm) high frame rate (up to kHz) imaging with SCExAO's internal camera.
  • Visible light (0.6-0.9 μm) imaging, with polarimetric and spectral differential imaging with the VAMPIRES instrument.
  • Visible light (0.6-0.9 μm) interferometry and polarimetric interferometry with the VAMPIRES instrument.
Additional capabilities are available on a shared risk basis, as they are currently under development and not yet sufficiently robust for open use.

SCExAO as a Technology Development Platform

SCExAO is also a development platform for high contrast imaging and high angular resolution techniques. New technologies are continuoulsy tested by our development team and collaborators. We provide and support SCExAO as a daytime testbed for R&D activities.

How does SCExAO work ?

SCExAO uses coronagraphy to block starlight while keeping planet image mostly unattenuated. We provide a range of coronagraph options depending on observation wavelength, contrast, and planet angular separation.

SCExAO relies on wavefront sensing and control techniques (commonly referred to as Adaptive Optics) to measure and correct in real-time the optical aberrations induced by Earth's atmosphere.

Imaging and Characterizing habitable planets around nearby stars

Our long-term goal is to enable imaging and spectrocopic characterization of nearby habitable planets with the upcoming generation of 30-m class telescopes. The SCExAO instrument is prototyping and validating the technologies (coronagraph, wavefront control, detectors, data analysis algorithms) that will be deployed on TMT, GMT and ELT to perform these challenging observations.

SCExAO can do this because it implements several a high efficiency, low inner working angle coronagraphs. The workhorse of these units is the PIAA (Phase Induced Amplitude Apodization), invented by Olivier Guyon (SCExAO project PI), that exhibits an inner working angle that is as close to the diffraction limit as you can get (1 λ/D). The PIAA used in SCExAO was designed to provide a raw-contrast of 106 at 1.5 λ/D. In addition SCExAO offers other low inner working angle coronagraphs such as the Vortex, Four-Quadrant Phase Mask and 8-Octant Phase Mask versions. In addition it also offers a shaped pupil coronagraph for high contrast work where the inner working angle can be relaxed.

SCExAO instrument

SCExAO mounted at the Nasmyth IR platform. AO188 can be seen to the left (large black box), SCExAO is a
three-level instrument in the middle (black and white panels) and modules CHARIS (the red instrument) and MEC (grey tower) are to the right of the image.

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