Recent science and engineering results with the laser guidestar adaptive optic system at Lick Observatory

Gavel, Donald T.; Gates, E. L.; Max, C. E.; Olivier, Scot S.; Bauman, Brian; Pennington, D. M.; Macintosh, Bruce; Patience, Jennifer; Brown, C.; Danforth, Pamela M.; Hurd, Randall L.; Severson, Scott; Lloyd, James P.

doi:10.1117/12.459680

Cited by 15 publications

(6 citation statements)

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“…All three errors share a common dependence on r 0 -5/3 . The mean wind speed at Lick is estimated at ∼ 13m/s using previous measurements 12, 14 of r 0 and f G .…”

Section: Probability Density Function Of the Instantaneous Strehl Ratiomentioning

confidence: 99%

“…As can be seen, there is a large variation in the Strehl ratio values ranging from highs ∼ 70% to lows ∼ 20% over time scales ∼ minutes or less. The 60,000 measurements for (PSFs [11][12][13][14][15][16] show the Strehl ratio to be changing on relatively fast time scales with a variable mean and large departures. This is also seen for PSFs 17-23.…”

Section: Strehl Ratio Measurementsmentioning

confidence: 99%

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Characterization of the Lick adaptive optics point spread function

2006

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We have investigated both the temporal and spatial structure of the point spread function (PSF) produced by the Lick Observatory adaptive optics (AO) system using the FastSub readout mode of the IRCAL camera using short-exposure images with exposure times of 22ms at a frame rate of ∼ 20Hz suitable for "freezing" the compensation under typical Kband observing conditions. These short exposures are a useful diagnostic tool for determining the system performance and permit measurement of the instantaneous Strehl ratio. Data taken from a number of observing runs, spanning over four months, show the underlying morphology of the PSF to be very stable with instantaneous Strehl ratios varying from ∼ 20%-70% in NGS mode. Estimates of the instantaneous Strehl distribution have also been obtained from which we have determined the probability density function for the distribution of the instantaneous Strehl ratios.

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“…All three errors share a common dependence on r 0 -5/3 . The mean wind speed at Lick is estimated at ∼ 13m/s using previous measurements 12, 14 of r 0 and f G .…”

Section: Probability Density Function Of the Instantaneous Strehl Ratiomentioning

confidence: 99%

Section: Strehl Ratio Measurementsmentioning

confidence: 99%

Characterization of the Lick adaptive optics point spread function

2006

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“…The landscape of AO, after a long period of evolution, is now prime for consolidation and standardization. Most of the deployed modern AO systems use Shack-Hartmann (SH) wavefront sensors [11][12][13][14][15][16] (WFS) while a few use pyramid WFS 17 and curvature sensors. 18,19 The wavefront sensing is followed by the computation of a correction vector through AO reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Scalable platform for adaptive optics real-time control, part 1: concept, architecture, and validation

Surendran

Burse

Ramaprakash

et al. 2018

J. Astron. Telesc. Instrum. Syst.

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We demonstrate a novel architecture for Adaptive Optics (AO) control based on FPGAs (Field Programmable Gate Arrays), making active use of their configurable parallel processing capability. SPARC's unique capabilities are demonstrated through an implementation on an off-the-shelf inexpensive Xilinx VC-709 development board. The architecture makes SPARC a generic and powerful Real-time Control (RTC) kernel for a broad spectrum of AO scenarios. SPARC is scalable across different numbers of subapertures and pixels per subaperture. The overall concept, objectives, architecture, validation and results from simulation as well as hardware tests are presented here. For Shack-Hartmann wavefront sensors, the total AO reconstruction time ranges from a median of 39.4µs (11 × 11 subapertures) to 1.283 ms (50 × 50 subapertures) on the development board. For large wavefront sensors, the latency is dominated by access time (∼1 ms) of the standard DDR memory available on the board. This paper is divided into two parts. Part 1 is targeted at astronomers interested in the capability of the current hardware. Part 2 explains the FPGA implementation of the wavefront processing unit, the reconstruction algorithm and the hardware interfaces of the platform. Part 2 mainly targets the embedded developers interested in the hardware implementation of SPARC.

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“…It has been demonstrated that AO systems can indeed work effectively with Laser Guide Stars (LGS), in the visible 1 and in the NIR 2 . Recently the Lick Observatory has achieved K-band Strehl values of~0.6 with LGS-AO.…”

Section: Introductionmentioning

confidence: 99%

VLT laser guide star facility

Bonaccini¹,

Allaert²,

Araujo³

et al. 2003

SPIE Proceedings

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We report on the ongoing VLT Laser Guide Star Facility project, which will allow the ESO UT4 telescope to produce an artificial reference star for the Adaptive Optics systems NAOS-CONICA and SINFONI. A custom developed dye laser producing >10W CW at 589nm is installed on-board of the UT4 telescope, then relayed by means of a single mode optical fiber behind the secondary mirror, where a 500mm diameter lightweight, f/1 launch telescope is projecting the laser beam at 90 km altitude. We described the design tradeoffs and provide some details of the chosen subsystems. This paper is an update including subsystems results, to be read together with our previous paper on LGSF design description 3 .

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Recent science and engineering results with the laser guidestar adaptive optic system at Lick Observatory

Cited by 15 publications

References 0 publications

Characterization of the Lick adaptive optics point spread function

Characterization of the Lick adaptive optics point spread function

Scalable platform for adaptive optics real-time control, part 1: concept, architecture, and validation

VLT laser guide star facility

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