&lt;title&gt;Field evaluation of two new continuous-wave dye laser systems optimized for sodium beacon excitation&lt;/title&gt;

Jacobsen, Bruce P.; Martínez, Ty; Angel, J. R. P.; Lloyd‐Hart, Michael; Benda, Steve M.; Middleton, Dave; Friedman, Herbert W.; Erbert, G.

doi:10.1117/12.176068

Cited by 18 publications

(7 citation statements)

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“…Circular polarization tends to trap atoms in a pair of states where decay into F' = 1 is forbidden by selection rules and is commonly referred to as optical pumping. Single-frequency cw experiments, dating back to 1994 by Jacobsen et al [7], found D 2a /D 2b = 3.5 for circularly-polarized light, 1.5 W of laser power and a 1.6 arc second mesospheric spot. When models were fit to their data, D 2a /D 2b = 2.1 was predicted for linearly-polarized light by Milonni et al [8].…”

Section: Guidestar Characterstics and Radiancementioning

confidence: 98%

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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Section: Guidestar Characterstics and Radiancementioning

confidence: 98%

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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“…The beam expander is a refractor with 48 cm diameter aperture, mounted close to the optical axis of the MMT array. 6 The beam typically has an elliptical gaussian profile of 1 8 x 12 cm FWHM and is focused to produce the smallest obtainable illuminated spot at the sodium layer. Guide star images recorded at the WFS have a typical FWHM of 1.1 arc sec, and appear as bright as a star of R 10 seen through an R filter.…”

Section: Sodium Lasermentioning

confidence: 99%

Final review of adaptive optics results from the preconversion MMT

et al. 1997

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The FASTTRAC II adaptive optics instrument has been used at the Multiple Mirror Telescope (MMT) for the past 2 years to provide improved image resolution in the near infrared. Results have been obtained using both natural guide stars and an artificial sodium laser beacon. With the imminent closure of the MMT prior to its conversion to a single-mirror 6.5 m telescope, FASTTRAC II has come to the end of its life. The instrument has been to the telescope for a total of 8 runs, and duringthat time it has been of enormous value both as a learning aid, demonstrating the requirements of its successor on the 6.5 m, and as a scientific tool.At this meeting, we present a selection of astrophysical data derived from FASTTRAC II, including the first closed-loop demonstration of an adaptive optics system using a sodium laser beacon. The sodium laser has been used to obtain near diffraction-limited near-infrared images of the core of M13, allowing the construction of a color-magnitude diagram to below the main sequence turnoff. Results have also been obtained from several gravitationally lensed quasars, and the cores of nearby galaxies in the local group.We also summarize work characterizing atmospheric conditions at the site. These studies have proceeded in two areasunderstanding the behavior of the phase perturbation with field angle and time, and characterizing the return from the sodium resonance beacon.

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“…The projector (Jacobsen et al 1994) collimated the outgoing beam with a lens of 50 cm diameter. As it left the telescope, the beam had a Gaussian proÐle with FWHM D 20 cm.…”

Section: Laser Beam Projectormentioning

confidence: 99%

“…Wavefront aberration will be measured by reference to a beacon created by a 10 W laser beam projected along the telescopeÏs optical axis (Jacobsen et al 1994). The laser, tuned to the line of D 2 atomic sodium, illuminates sodium atoms in the mesosphere.…”

Section: Introductionmentioning

confidence: 99%

Verification of a System to Prevent Aircraft Illumination by Adaptive Optics Laser Beacons

Lloyd‐Hart

Cheselka

Hanson

1999

PUBL ASTRON SOC PAC

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ABSTRACT. Laser beams directed into the sky from astronomical observatories to generate guide beacons for adaptive optics image-sharpening systems are a potential hazard to aircraft. Detection systems are needed to sense aircraft and interrupt the laser beam to prevent accidental illumination. We describe here a system designed for this task. A computer examines CCD images of the sky over a wide Ðeld of view and uses a motion detection algorithm to Ðnd tracks made by aircraft lights. The results of tests, conducted with simultaneous radar coverage from Tucson International Airport, are reported. A test with an actual laser beacon at the Multiple Mirror Telescope in which Mars was used as a simulated aircraft is also described.

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<title>Field evaluation of two new continuous-wave dye laser systems optimized for sodium beacon excitation</title>

Cited by 18 publications

References 1 publication

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

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

Final review of adaptive optics results from the preconversion MMT

Verification of a System to Prevent Aircraft Illumination by Adaptive Optics Laser Beacons

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