Progress toward a 50-watt facility-class sodium guide star pump laser

Fugate, Robert Q.; Denman, Craig A.; Hillman, Paul D.; Moore, Gerald; Telle, John M.; Rue, Imelda A. De La; Drummond, Jack D.; Spinhirne, J. M.

doi:10.1117/12.556871

Cited by 12 publications

(10 citation statements)

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“…Significantly more pixels per subaperture will also be required (8x2 or 16x4 vs. a 2x2 quadrant detector) to implement noise-optimal wavefront sensing methods. 14,15 Three facilitized copies of an existing laser system would suffice to meet our requirements for total laser power, 16 and a pulsed laser system does not appear to be necessary to achieve adequate wavefront sensing measurement accuracy. The baseline wavefront sensing detector for NFIRAOS is the radial format CCD array currently under development via the AO Development Program (AODP), 11 which would offer improved measurement accuracy and reduced pixel rates with or without a pulsed laser.…”

Section: Ao Modementioning

confidence: 98%

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Adaptive optics for the Thirty Meter Telescope

et al. 2005

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Adaptive Optics (AO) will be essential for at least seven of the eight science instruments currently planned for the Thirty Meter Telescope (TMT). These instruments include three near infra-red (NIR) imagers and spectrometers with fields of view from 2 to 30 arc seconds, a mid-IR echelle spectrometer, a planet formation imager/spectrometer, a wide field optical spectrograph, and a NIR multi-object spectrometer with multiple integral field units deployable over a 5 arc minute field of regard. In this paper we describe the overall AO reference design that supports these instruments, which consists of a facility AO system feeding the first three instruments and dedicated AO systems for the remaining four.Key design challenges for these systems include very high-order, large-stroke wavefront correction, tip-tilt sensing with faint natural guide stars to maximize sky coverage, laser guidestar wavefront sensing on a very large aperture, and achieving extremely high contrast ratios for the detection of extra-solar planets and other faint companions of bright stars. We describe design concepts for meeting these challenges and summarize our supporting plans for AO component development.

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Section: Ao Modementioning

confidence: 98%

“…16 Approximately 35W has been projected onto the sky. 26 A similar solid-state laser producing 12-15W average power has been delivered to Gemini Observatory by Coherent Technologies, Incorporated, and the prospects of scaling this design to the 50W level are good.…”

Section: Real-time Control (Rtc) Electronicsmentioning

confidence: 99%

Adaptive optics for the Thirty Meter Telescope

et al. 2005

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“…During Fall 2004, the Directed Energy Directorate of the Air Force Research Laboratory installed a 50 W cw sodium wavelength fasor on the Starfire Optical Range (SOR) 3.5-m adaptive optical telescope [2,3]. Implementation of the sodium LGS system, its integration with the 3.5-m facility, and its first-light guidestar sky tests have been conducted through 2005-2006.…”

Section: The 50-w Sodium Guidestar Fasormentioning

confidence: 99%

Characteristics of sodium guidestars created by the 50-watt FASOR and first closed-loop AO results at the Starfire Optical Range

et al. 2006

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A computer-automated cw sodium guidestar FASOR (Frequency Addition Source of Optical Radiation) producing a single frequency 589-nm beam with up to 50 W for mesospheric beacon generation has been integrated with the 3.5-m telescope at the Starfire Optical Range, Kirtland AFB, New Mexico. Radiance tests have produced a peak guidestar V 1 magnitude = 5.1 (~7000 photons/s/cm 2 at zenith) for 30 W of circularly polarized pump power in November 2005. Estimated theoretical maximum guidestar radiance is about 3 times greater than measured values indicating saturation due to atoms possibly becoming trapped in F' = 1 and/or atomic recoil. From sky tests over 3.5 years, we have tracked the annual variation of the sodium column density by measuring the return flux as a function of fasor power and determining the slope at zero power. The maximum occurs on October 30 and the minimum on May 30, with corresponding predicted returns of 8000 (V 1 = 4.8) and 3000 (V 1 = 5.8) ph/s/cm 2 with 50 W of fasor power and circular polarization. The effect of the Earth's magnetic field on the radiance of the sodium laser guidestar (LGS) from various azimuths and elevations has been measured. The peak return flux over our observatory occurs at [az=198°; el=+71°], compared with the direction of the magnetic field lines at [190°; +62°], and it can vary by a factor of 3 over the sky above el = 30°. First results for non-optimized sodium LGS adaptive optics (AO) closed-loop operation have been obtained using binary stars. Strehl ratios of 0.03 have been measured at 850 nm and a 0.14 arc second binary star has been resolved during first closed loop observations. Guidestar characteristics, including radiance, size, and Rayleigh backscatter, the sodium LGS wavefront sensor (WFS) AO system, and recent closed-loop results on binary stars are presented.

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“…We believe it to be about 10kHz. We have built two fasors, a 20-watt table-top version, 3,4 and a 50-watt automated version 5,6 which has been mounted on the 3.5-meter telescope at the site. The 589 nm is produced by resonant sum-frequency mixing of the 1064-nm and 1319-nm Nd:YAG laser lines in a bow-tie-shaped cavity.…”

Section: Guidestar Pump Fasormentioning

confidence: 99%

“…It is mounted on the azimuthal base of the telescope along with 3 short racks that hold electronics and a cooling water distribution system. The water chiller and diode laser power supplies are located off the telescope gimbal one story below near the control room 6 . Figure 1 shows the results of 8 scans of guidestar radiance vs. pump fasor wavelength in August, October, November and December of 2005.…”

Section: Guidestar Pump Fasormentioning

confidence: 99%

Studies of a mesospheric sodium guidestar pumped by continuous-wave sum-frequency mixing of two Nd:YAG laser lines in lithium triborate

et al. 2006

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Mesospheric sodium guidestar radiance is plotted vs. wavelength, fasor power, fasor polarization and date. Peak radiance for circular polarization was about 7000 photons/sec/cm 2 (V 1 magnitude = 5.1) for 30 watts of pump power in November of 2005. Pumping with circular polarization at high power produces about 2 times more return than linear polarization. Pumping D2a at high power produces about 12 times more return than pumping D2b. A lidar equation is used to determine column density. Estimated maximum possible guidestar radiance is about 3 times greater than measured values. Guidestar radiance may be saturated by atoms becoming trapped in F′=1 and atomic recoil.

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Progress toward a 50-watt facility-class sodium guide star pump laser

Cited by 12 publications

References 0 publications

Adaptive optics for the Thirty Meter Telescope

Adaptive optics for the Thirty Meter Telescope

Characteristics of sodium guidestars created by the 50-watt FASOR and first closed-loop AO results at the Starfire Optical Range

Studies of a mesospheric sodium guidestar pumped by continuous-wave sum-frequency mixing of two Nd:YAG laser lines in lithium triborate

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