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November 7, 202211:30 am – 12:30 pm (CDT)

Progress Towards Adaptive Optics at Visible Wavelengths with a Laser Guide Star


Mark Ammons (Lawrence Livermore National Laboratory)


Justin Spilker



Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

Adaptive Optics, a technology that compensates for the blurring caused by atmospheric turbulence, is now a common observing modality in astronomical telescopes and imaging systems.  Sodium Laser Guide Stars (LGS), pointable beacons first developed by the US Air Force, have extended the sky coverage of AO systems on today’s generation of large optical telescopes to most of the sky.  LGSs have played a role in the mass measurement of the Milky Way’s central black hole, as recognized by the 2020 Nobel Prize in physics shared by Ghez, Penrose, and Genzel.  I will describe ongoing work using the ShaneAO LGS at Lick Observatory to measure parallaxes of extremely faint T brown dwarfs.  A major limitation of LGS AO systems has been that they are most effective at near-infrared wavelengths ( > 1 micron) and have not yet reached usable image quality at visible wavelengths.  LLNL has started a program to develop a laser guide star AO system with a goal of obtaining diffraction-limited cores at visible wavelengths (~500 nm) at Lick Observatory.  This AO system will use computationally efficient reconstructor algorithms and predictive control techniques pioneered with the Gemini Planet Imager.  I will also describe the relevance of the work for Extremely Large Telescopes such as TMT and GMT.

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