Adaptive Optics at the Institute for AstronomyThe Adaptive Optics Laboratory at the Institute for Astronomy (IfA), led by Mark Chun, Christoph Baranec, and Mike Bottom, develop innovative technologies and systems that counteract the image-blurring effect of Earth's atmosphere. The ‘imaka project, led by Chun, is working toward extremely large corrected fields of view at visible and near-infrared wavelengths. By correcting for the atmosphere just close to the telescope, the team has demonstrated corrected fields of view larger than previously thought possible. Robo-AO, led by Baranec, is a fully robotic system that can observe hundreds of objects per night at near Hubble Space Telescope resolution. Mike Bottom develops extreme adaptive optics for ground-based telescopes and develops new photon-counting near-infrared detectors for ground and space high contrast imaging.
Current Adaptive Optics Projects
`Imaka is an instrument concept for an extremely wide-field ground-layer adaptive optics on Maunakea, Hawaii. The instrument leverages Maunakea’s unique conditions: excellent seeing, weak free-atmosphere seeing, and its highly-confined boundary layer turbulence with a ground-layer adaptive optics system to deliver high-resolution images over fields of view of several tens of arcminutes. The `imaka instrument on the UH2.2-meter telescope provides some of the finest wide-field images ever obtained from the ground over a field of view nearly an order of magnitude larger than other sites. The current work includes the design and fabrication of an adaptive secondary mirror (ASM) for the UH 2.2-meter telescope using a new actuator technology developed by TNO (Nederlands). We plan to deploy the ASM in 2021. The project is aptly named after the Hawaiian word `imaka meaning “scenic viewpoint”.
Wavefront sensing in the infrared is highly desirable for the study of M-type stars and cool red objects, as they are sufficiently bright in the infrared to be used as the adaptive optics guide star. This aids in high contrast imaging, particularly for low mass stars where the star-to-planet brightness ratio is reduced. The combination of infrared detector technology with the highly sensitive Pyramid wavefront sensor (WFS) can extend the capabilities of current telescopes and meet the requirements for future instruments, such as those proposed for the giant segmented mirror telescopes. We built the infrared Pyramid WFS for Keck, a key sub-system of the Keck Planet Imager and Characterizer (KPIC), that takes advantage of the combination. The Keck infrared pyramid wavefront sensor project was lead at IfA by Charlotte Bond (now at UKATC).
Low noise infrared detectors are key technologies for both wavefront sensing in ground-based adaptive optics and for imaging and spectroscopy of exo-Earths in future space telescopes. Here at the IfA, we are leading the development of linear-mode avalanche photodiode arrays (LmAPDs), one such promising technology. These arrays have already found use as high-speed, low-noise wavefront sensors for adaptive optics systems at Subaru and Keck, and have been baselined as the sensors for the cameras of the future space telescopes HabEx and LUVOIR. This project, which is maturing large format LmAPDs for spaceflight readiness and ground based astronomy, continues the pioneering work of the late professor Don Hall.
Extreme adaptive optics on ground-based telescopesImaging exoplanets places extreme demands on the level of wavefront control required in a telescope. Typically, the total amount of optical error needs to be a small fraction of a wavelength. We are working on developing algorithms to sense and control the wavefront error in large ground-based telescopes to these fine levels, using the techniques of focal-plane wavefront control and predictive control of adaptive optics. We work closely with our colleagues at Keck observatory and Subaru to develop and test these technologies in the lab and on-sky.
People Working at the Lab
- Dora Fohring
- Charles-Antoine Claveau
IfA Graduate Students
- Maisa Salama
- Ryan Dungee
- James Ou
- Miles Lucas
- Jingwen Zhang
- Suzanne Zhang