First tests of wavefront sensing with a constellation of laser guide beacons

M. Lloyd-Hart, C. Baranec, N. M. Milton, T. Stalcup, M. Snyder, N. Putnam, J Roger P Angel

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Adaptive optics to correct current telescopes over wide fields, or even to correct future very large telescopes over narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such measurements, made at the 6.5 m MMT with five Rayleigh beacons in a 2× pentagon. Each beacon is made with a pulsed beam at 532 nm of 4 W at the exit pupil of the projector. The return is range-gated from 20 to 29 km and recorded at 53 Hz by a 3 6-element Shack-Hartmann sensor. Wavefronts derived from the beacons are compared with simultaneous wavefronts obtained for individual natural stars within or near the constellation. Observations were made in seeing averaging 1.″0 with two-thirds of the aberration measured to be from a ground layer of mean height 380 m. Under these conditions, subtraction of the simple instantaneous average of the five beacon wavefronts from the stellar wavefronts yielded a 40% rms reduction in the measured modes of the distortion over a 2′ field. We discuss the use of multiple Rayleigh beacons as an alternative to single sodium beacons on 8 m telescopes and the impact of the new work on the design of a multi-sodium beacon system for the 25 m Giant Magellan Telescope.

Original languageEnglish (US)
Pages (from-to)679-686
Number of pages8
JournalAstrophysical Journal
Volume634
Issue number1 I
DOIs
StatePublished - Nov 20 2005

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beacons
constellations
laser
sodium
lasers
telescopes
sensor
test
projectors
pupils
adaptive optics
subtraction
aberration
time measurement
stars
sensors

Keywords

  • Atmospheric effects
  • Instrumentation: adaptive optics
  • Instrumentation: high angular resolution
  • Telescopes

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Lloyd-Hart, M., Baranec, C., Milton, N. M., Stalcup, T., Snyder, M., Putnam, N., & Angel, J. R. P. (2005). First tests of wavefront sensing with a constellation of laser guide beacons. Astrophysical Journal, 634(1 I), 679-686. https://doi.org/10.1086/496960

First tests of wavefront sensing with a constellation of laser guide beacons. / Lloyd-Hart, M.; Baranec, C.; Milton, N. M.; Stalcup, T.; Snyder, M.; Putnam, N.; Angel, J Roger P.

In: Astrophysical Journal, Vol. 634, No. 1 I, 20.11.2005, p. 679-686.

Research output: Contribution to journalArticle

Lloyd-Hart, M, Baranec, C, Milton, NM, Stalcup, T, Snyder, M, Putnam, N & Angel, JRP 2005, 'First tests of wavefront sensing with a constellation of laser guide beacons', Astrophysical Journal, vol. 634, no. 1 I, pp. 679-686. https://doi.org/10.1086/496960
Lloyd-Hart M, Baranec C, Milton NM, Stalcup T, Snyder M, Putnam N et al. First tests of wavefront sensing with a constellation of laser guide beacons. Astrophysical Journal. 2005 Nov 20;634(1 I):679-686. https://doi.org/10.1086/496960
Lloyd-Hart, M. ; Baranec, C. ; Milton, N. M. ; Stalcup, T. ; Snyder, M. ; Putnam, N. ; Angel, J Roger P. / First tests of wavefront sensing with a constellation of laser guide beacons. In: Astrophysical Journal. 2005 ; Vol. 634, No. 1 I. pp. 679-686.
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