Towards Ideal Adaptive Optics Performance with Focal-plane Wavefront Sensing

Adaptive optics (AO) is a revolutionary optical system which corrects errors caused by the atmosphere which affect ground-based telescopes. These systems vastly improve the resolution of ground-based astronomy, making it possible to observe farther and fainter objects than ever before, including direct imaging of exoplanets. Modern AO systems are limited by errors in the optical systems which are invisible to the AO, but can negatively affect the scientific images. One of the main errors is caused by misalignment of the segments of the primary mirrors. This will be even more of an issue for the newest generation of large telescopes. Fast and Furious is a newly developed technique which uses the science image and information from the AO system to estimate and correct these errors. The investigators have worked to make this algorithm usable on a single science camera and AO mode, usually used to image exoplanets. For this project, the investigator will now expand this algorithm to be used for all AO instruments and modes at the W. M. Keck Observatory. This will pave the way for new science cases, such as galactic center observations and spectroscopy, and will improve the quality of observations for a significant fraction of the available observing time. This project will also help to develop a diverse workforce by funding undergraduates from under-represented communities and training a graduate student in AO, addressing the shortage of AO expertise in the United States. Modern adaptive optics (AO) systems are shown to be mainly limited by quasi-stable systematics errors. Many of these are caused by segmented mirror co-phasing and optical figure errors not seen by the wavefront sensor. The investigator has recently implemented a real-time method of correcting these errors at the W. M. Keck Observatory using the science camera image and a focal-plane wavefront sensing algorithm. This technique, known as Fast and Furious, requires no additional hardware, converges within minutes, can be run concurrently with science, and works reliably to improve AO performance. The current implementation is limited to a single science instrument and one AO mode (natural guide star with pupil tracking) usually used for exoplanet observations. The investigator will implement this algorithm for general use for the Keck Observatory community to positively impact all AO fed science regardless of science goals. Additionally, the investigator will explore in more detail the type of optical errors Fast and Furious is correcting. Error sources such as segment co-phasing errors or non-common path aberrations are of great interest to the future large telescope projects, all of which rely on segmented apertures and AO fed instruments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2408872 | Program: 01002425DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Charlotte Guthery | Institution: California Association for Research in Astronomy, KAMUELA, HI | Award Amount: $388,823 View on NSF Award Search: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2408872 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2408872.html