Astronomical adaptive optics systems can be classified into two basic types: 1) a standard telescope equipped with an adaptive optics bench that includes transfer optics, wavefront sensors, filters, and one or more deformable mirrors, and 2) a system that incorporates an adaptive secondary mirror (ASM) directly into the telescope itself, reducing the number of reflections and preserving a clean optical system all the way to the instrument focus. The latter scheme is in some ways more difficult and expensive to achieve, but has demonstrated the highest on-telescope image quality, as well as providing far better performance in the infrared.
The sole example of installed ASM technology in the southern hemisphere is the 585 actuator secondary installed by Dr. Laird Close and collaborators from The University of Arizona and Arcetri Observatory (Italy) on the 6.5m Clay Magellan telescope at Las Campanas, Chile. With the mirror now in place, Dr. Close is planning instrumental upgrades to make use of the greatly sharpened images. Two improvements are proposed: 1) enhanced electronics and a ?smart?, high-speed shutter that will limit exposure only to intervals of excellent correction and thereby enable high-resolution imaging in the optical (wavelengths of ~0.6 nm), and 2) precise coronagraphic masks and vibration control to allow 1-5 micron imaging and spectroscopy of sources in the AO-sharpened field with a bright central object obscured. Initial science to be performed with these systems includes high-contrast imaging of reflected visible light from mature giant exoplanets (a key step towards discovering true Earths), the mass-loss from evolved stars, structures of ionized gas regions around hot stars, surfaces of solar-system asteroids and moons, and high-contrast L and M band (3.5 and 5 microns) imaging/spectroscopy of newly-discovered young dusty exoplanets.
Dr. Close has demonstrated an excellent history of mentoring and collaborating with students and young faculty, and his current activities are no exceptions. The new adaptive optics detector systems will also be made available to others with access to the Magellan telescopes, and hopefully to the general astronomical community when public access to privately-funded facilities is renegotiated.
Funding for the development of new imaging and spectroscopic capabilities for the Magellan telescope adaptive optics systems is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.
