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Proceedings Paper

Sky tests of a laser-pumped sodium guidestar with and without beam compensation
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Paper Abstract

Three sets of sky tests have been conducted at the Starfire Optical Range with a continuous-wave, single-frequency, 20-W laser in preparation for a 50-W facility-class laser. Brightness measurements were made of the sodium guidestar produced with and without adaptive optics (AO) correction to the outgoing laser beam when it was either linearly or circularly polarized. Correcting for the transmission of our V filter at the sodium wavelength, a circularly polarized laser beam of 12 W out the telescope produced a guidestar of V=7.1 (1015 ph/s/cm2 at the top of the telescope). In general, a circularly polarized beam produces a guidestar between 75 and 100% brighter than a linearly polarized beam, indicating a significant degree of optical pumping of the sodium D2-line magnetic sublevels. However, guidestars produced with beams launched with tip-tilt correction only were 11% brighter than with beams launched with full AO correction. From deconvolved images of the guidestar taken with the 3.5-m telescope, the smallest spot, produced from a beam with 8.5 W of power out the telescope, circular polarization, and launched closed loop, had a Gaussian FWHM of 0.85 arcsec, or 38 cm at an altitude of 92 km. This corresponds to a peak Gaussian intensity of 3.8 mW/cm2.

Paper Details

Date Published: 25 October 2004
PDF: 11 pages
Proc. SPIE 5490, Advancements in Adaptive Optics, (25 October 2004); doi: 10.1117/12.556869
Show Author Affiliations
Jack D. Drummond, Air Force Research Lab. (United States)
John M. Telle, Air Force Research Lab. (United States)
Craig A. Denman, Air Force Research Lab. (United States)
Paul D. Hillman, Air Force Research Lab. (United States)
James M. Spinhirne, The Boeing Co. (United States)
Julian C. Christou, Univ. of California/Santa Cruz (United States)

Published in SPIE Proceedings Vol. 5490:
Advancements in Adaptive Optics
Domenico Bonaccini Calia; Brent L. Ellerbroek; Roberto Ragazzoni, Editor(s)

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