Sodium-layer laser-guide-star experimental results

Avicola, K.; Brase, James M.; Morris, J. R.; Bissinger, H. D.; Duff, J. M.; Friedman, Herbert W.; Gavel, Donald T.; Max, C. E.; Olivier, Scot S.; Presta, Robert W.; Rapp, D. A.; Salmon, J. T.; Waltjen, Kenneth E.

doi:10.1364/josaa.11.000825

Cited by 29 publications

(16 citation statements)

References 10 publications

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“…The brightness of the sodium beacon depends on the laser characteristics: the pulse duration and the repetition rate governing the saturation of the sodium D 2 transition, and the possibility of optical pumping effects increasing the efficiency of the atomic excitation. To produce sodium beacons, Jelonek et al (1994) used a sum frequency mode‐locked YAG laser, while others (Avicola et al 1994; Friedman et al 1994; Olivier et al 1994) used a pulsed YAG‐pumped dye laser. Theoretical calculations of Milonni et al for a pulsed laser give very good agreement with experimental results (Milonni, Fugate & Telle 1998) and explain the difference of excitation efficiency of different lasers.…”

Section: Long‐term Variations Of the Layermentioning

confidence: 99%

Characterization of the mesospheric sodium layer at La Palma

Michaille

Clifford

Dainty

et al. 2001

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TWe present the results of a mesospheric sodium monitoring programme at La Palma carried out through five campaigns of one week each, from 1999 September to 2000 August. The yearly averaged parameters of the layer (the sodium column density and the width) are given. We show that the short time-scale dynamics of the layer are governed by the sporadic layers with an average frequency of one event per night. The influence of the short time-scale dynamics of the layer on an adaptive optics system working on the William Herschel Telescope is quantified. It appears that it is a small effect in terms of defocus error. Finally, we present data obtained during the Perseid meteor shower and show that the dynamics of the sodium layer undergoes a transition with the meteoric activity.

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Section: Long‐term Variations Of the Layermentioning

confidence: 99%

Characterization of the mesospheric sodium layer at La Palma

Michaille

Clifford

Dainty

et al. 2001

Monthly Notices of the Royal Astronomical Society

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“…4) for a natural guide star and a laser guide star are similar. For both systems adaptive optics decreases residual phase fluctuations at low frequencies, with the correction losing its impact at frequencies greater than [5][6][7][8][9][10] Hz. The noise floor above 10 Hz (Fig.…”

Section: E Maxmentioning

confidence: 99%

Image Improvement from a Sodium-Layer Laser Guide Star Adaptive Optics System

Max

Olivier

Friedman

et al. 1997

Science

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162

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“…Several groups in the world have begun to explore the use of sodium laser guide star technique for astronomical adaptive optics (e.g. Jacobsen et al 1993;Jelonek et al 1994;Avicola et al 1994). In the Fall 1996, our group has successfully closed the laser guide star adaptive optics tip-tilt system loop and make improvements in the image quality (Lloyd-Hart et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Simultaneous measurements of sodium column density and laser guide star brightness

Jacobsen

Angel

et al. 1998

SPIE Proceedings

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We report on new results of simultaneous measurements of sodium layer column density and the absolute return flux from laser guide stars created by a monochromatic 1 W CW laser, tuned to the peak of the sodium D2 hyperfine structure. The return was measured at the MMT while the sodium abundance was measured at the CFA 60 inch telescope, about 1 km away, with the Advanced Fiber Optic Echelle (AFOE) spectrograph. The laser frequency stability, which can greatly affect the return flux, was monitored at the same time in order to improve the measurement accuracy. After the correction for laser frequency jitter and atmospheric transmission, the absolute flux return above the atmosphere for circularly polarized light is 1.2(±O.3) x 1O photons m2 per watt launched above the atmosphere, per unit column density, which we take as our measured mean over the year of N(Na) = 3.7x 1O cm2 at Tucson. The solidification of a final well-determined relationship between the sodium laser guide star brightness and sodium layer column density is pivotal in the design of the next generation laser guide star adaptive optics systems.We also report the measurements and analysis of the relationship between the projected beam waist of the sodium laser and the resultant spot size on the sodium layer under typical atmospheric conditions. Since wavefront measured error is proportional to spot size, and also to 1/Jiver, minimum spot size is crucial for lowest laser power requirement. By projecting the laser through diffraction limited optics of 0.5 m diameter, roughly 3 r0, we have achieved the smallest artificial beacon yet recorded, about 0.8 arcsec.

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Sodium-layer laser-guide-star experimental results

Cited by 29 publications

References 10 publications

Characterization of the mesospheric sodium layer at La Palma

Characterization of the mesospheric sodium layer at La Palma

Image Improvement from a Sodium-Layer Laser Guide Star Adaptive Optics System

Simultaneous measurements of sodium column density and laser guide star brightness

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