Dr. Greg Burton Profile

Dr. Greg Burton

at Lawrence Livermore National Lab

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Author

Publications (2)

Proceedings Article | 13 December 2020 Poster

LLAMAS: enabling higher contrast with the low-latency adaptive mirror system

S. Mark Ammons, Brian Bauman, Greg Burton, Doug Homoelle, Mike Kim, David Palmer, Robert Panas, Paul Pax, Lisa Poyneer, Jayke Nguyen, Princess Corral

Proceedings Volume 11448, 114482P (2020) https://doi.org/10.1117/12.2563074

KEYWORDS: Adaptive optics, Mirrors, Sensors, Point spread functions, Turbulence, Planets, Gemini Planet Imager, Microelectromechanical systems, Wavefront sensors, Modulation

Proceedings Article | 18 July 2018 Presentation + Paper

LLAMAS: low-latency adaptive optics at LLNL

S. Mark Ammons, Brian Bauman, Greg Burton, Chris Gates, Jay Dawson, Brian Hackel, Doug Homoelle, Michael Kim, Glenn Larkin, David Palmer, Robert Panas, Paul Pax, Lisa Poyneer

Proceedings Volume 10703, 107031N (2018) https://doi.org/10.1117/12.2314281

KEYWORDS: Adaptive optics, Wavefront sensors, Gemini Planet Imager, Sensors, Actuators, Mirrors, Turbulence, Deformable mirrors, Wavefronts, Control systems

Read Abstract +

The performance of high-contrast AO instruments (GPI, SPHERE, ScEXAO, MagAO) and other systems that operate at visible wavelengths can be severely hampered by control system latencies and temporal wavefront errors. In high-contrast systems, temporal errors and delays are manifest as high spatial frequency wavefront residuals that scatter light into the controllable region of the PSF and diminish contrast, an effect that is particularly severe when atmospheric coherence times are short. Solutions that have been proposed include lower latency electronics, deformable mirrors with lower mechanical response times, and specialized control algorithms such as predictive control. These advancements will be necessary for achieving the latency goals of high actuator count systems on future Extremely Large Telescopes (ELTs), including NFIRAOS+ and PFI on the Thirty Meter Telescope, upgrading the performance of existing highcontrast systems, and pushing adaptive optics to visible wavelengths. LLAMAS (Low-Latency Adaptive Optical Mirror System) is a fully funded adaptive optics system at the Lawrence Livermore National Laboratory site that will test these techniques in an integrated, real time, closed-loop AO system. With a total system latency goal of ~100 microseconds (including mechanical response time, not including frame integration), LLAMAS will achieve an order of magnitude improvement in AO system latencies over the current generation of high-contrast AO systems. The woofer/tweeter architecture will incorporate a 492-actuator Boston Micromachines MEMS device mapping 24 actuators across a circular pupil. The tweeter mirror will be paired with a specialized low-latency driver, delivering less than 40 microseconds electronic and mechanical latency (10 – 90%). The real-time control computer will utilize the computationally efficient Fourier Transform Reconstructor with a predictive Kalman filter with a goal of completing all computations and reconstructing the wavefront in less than 20 microseconds. LLAMAS will be fully integrated with a 21×21 lenslet Shack-Hartmann sensor by January 2019. These proceedings describe the LLAMAS design, characterize the performance of its low-latency componentry, and discuss the relevance of the design for future high-contrast, visiblelight, and high actuator count AO systems on ELTs.

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