Extreme Adaptive Optics
The technology behind high contrast imaging of exoplanets
Astronomer, Steward Observatory
Professor, University of Arizona
About the Lecture
Adaptive optics (AO) systems are used in astronomical telescopes to reduce or eliminate the wavefront distortion that arises in light as it passes through the atmosphere. In advanced astronomical observatories AO systems work by measuring the wavefront distortions and introducing a complementary distortion into a deformable reflector in the optical path that cancels out the distortions.
Extreme AO systems that can provide super-resolved imaging for the very largest ground based telescopes are technically challenging to design and build. They involve complex sensors to determine the wavefront distortion, sensitive and fast actuators to shape the correcting surface, typically include lasers to produce a synthetic guide star of known properties in the upper atmosphere, and high speed computers to calculate actuator adjustments in real time, and electronic controls to effectuate the adjustments many times per second.
The most ambitious and demanding type of adaptive optics, referred to as Extreme Adaptive Optics (XAO), is designed to image exoplanets. XAO systems operate at high speed, well above 1 kHz, and employ deformable mirrors with many actuators, typically over 1,000. They rely on fast low-noise detector technologies to measure incoming optical aberrations with nanometer-level precision, and high-performance computing hardware to process incoming data in real-time. Thanks to recent advances in optics, detectors and computing, XAO systems are becoming highly integrated systems where multiple components actively participate in correcting atmospheric distortion and measuring, removing and calibrating unwanted stellar light. Advances in these systems now being developed will enable the extremely large telescopes now being planned and built to image habitable exoplanets.
This lecture will discuss the physics and engineering of XAO systems including the Subaru Extreme Adaptive Optics system that currently is prototyping such approaches.
Note: This lecture augments Olivier’s previous lecture on AO, given on October 8, 2021 at the Society’s 2,446th meeting. Minutes of that meeting and a video recording of the lecture are available on the PSW website at https://pswscience.org/meeting/2446/.
Reading on Topic
1, Olivier Guyon (2018): “Extreme Adaptive Optics”, Annual Review of Astronomy and Astrophysics, Vol. 56, pgs 315-355
2. Stephan Hippler (2019): “Adaptive Optics for Extremely Large Telescopes”, Journal of Astronomical Instrumentation, Vol. 8, No 2: 1950001–322; arXiv:1808.02693. Bibcode:2019JAI…..850001H. doi:10.1142/S2251171719500016. S2CID 119505402.
3. Duffner et al. (2009): The Adaptive Optics Revolution: A History, University of New Mexico Press, ISBN 978-0-8263-4691-9.
4. Guyon et al. (2021): High contrast imaging at the photon noise limit with self-calibrating WFS/C systems, Proc SPIE, Volume 11823, id. 1182318 11 pp; DOI: 10.1117/12.2594885 ; https://arxiv.org/abs/2109.13958
5. Guyon et al. (2020): Adaptive optics real-time control with the compute and control for adaptive optics (Cacao) software framework, Proc SPIE 11448, Adaptive Optics Systems VII, 114482N; https://doi.org/10.1117/12.2562822P
6. The SEEDS High Contrast Imaging Survey of Exoplanets around Young Stellar Objects
arXiv.org > astro-ph > arXiv:1604.04697
7. “Optical tricks to image and study habitable exoplanets” SETI institute lecture 2013 – https://www.youtube.com/watch?v=Da2KLcbUIV8
8. “The search for other Earth-like planets” TED-Ed – https://www.youtube.com/watch?v=JTNY92xeFS0
About the Speaker
Olivier Guyon is Professor in the Department of Astronomy and Astronomer in the College of Optical Sciences and the Steward Observatory at the University of Arizona. He also is Affiliated Professor with the Astrobiology Center of the Japanese National Institutes of Natural Sciences and serves as Extreme Adaptive Optics Project Scientist for the Subaru Telescope of the National Astronomical Observatory of Japan. He is also a member of the Magellan extreme-AO development team.
Currently Olivier is developing high contrast imaging techniques for current and future ground and space-based telescopes, particularly innovative techniques for detecting and characterizing extrasolar planets. His research includes work on coronagraphy, wavefront sensing techniques for Adaptive Optics, and astrometry.
Olivier developed the Phase-Induced Amplitude Apodization (PIAA) Coronagraph, a highly efficient optical device to mask light from a star while preserving light from planets around it. And he is currently leading the Subaru Coronagraphic Extreme Adaptive Optics group at the Subaru Telescope to use these new techniques on the Subaru telescope for exoplanet detection and characterization.
Oliver is an author on over 169 refereed publications and more than 486 non-refereed publications. Among other honors and awards he is a MacArthur fellowship, a recipient of a Presidential Early Career Award for Scientists and Engineers, and of the Guinier Young Researcher Award of the French Society of Physics
Olivier earned his undergraduate degree at the École Normale Supérieure of Paris and his PhD in Astronomy at the University Paris.