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1、Laser guide star adaptive optics at the Keck Observatory,Adam R. Contos, Peter L. Wizinowich, Scott K. Hartman, David Le Mignant, Christopher R. Neyman, Paul J. Stomski, Jr., and Douglas Summers W.M. Keck Observatory SPIE Astronomical Telescopes and Instrumentation Conference 23 August 2002, Waikolo
2、a, HI,4389 - 42,Talk Outline,Overview Sky Coverage for LGS and NGS Modes Optical Path New LGS AO Hardware System Upgrades & Issues Laser Guide Star Future Summary,Overview,Traditional AO with NGS Bright star in close proximity 1% coverage Sodium LGS for nearly complete coverage Still require an NGS,
3、 but can be much dimmer Keck II System Upgrades for LGS AO Low Bandwidth Wavefront Sensor (LBWFS) Tip/Tilt Sensor (TTS), using quad-cell APDs Software control Laser system (described in following talk) Scheduled for integration in 2003,Sky Coverage: NGS and LGS,1Bahcall 2Keck Report 208, 1996.,NGS,L
4、GS,Optical Path,Highlighted AO Bench Elements: 1-Image Rotator 2-Tip/Tilt Mirror 4-Deformable Mirror 6-IR Dichroic 12-Sodium Dichroic 13-Field Steering Mirrors 14, 15-Wavefront Sensing Camera and Focus Camera Stage 17-Beamsplitter 18-Low Bandwidth Wavefront Sensor, Tip/Tilt Sensor & Stage 19-Acquisi
5、tion Camera,LBWFS & TTS Description,Low Bandwidth Wavefront Sensor Shack-Hartmann lenslet array sensor 304 subapertures (240 active) Photometrics 512x512 CCD detector Readout every few sec. to few min. Tip/tilt Sensor Quad-lens Fiber-fed APDs Mounted on 3-axis tip/tilt stage Beamsplitter cube 90% to
6、 TTS, 10% to LBWFS,System Upgrades & Issues (1),System Upgrades & Issues (2),System Upgrades & Issues (3),1st Laser Propagation (12/01),Laser power 17 W FWHM 1.4” (seeing 1”) Magnitude 9.5,Future,Summary of LGS AO at Keck,Achieved first laser propagation AO upgrades being incorporated for LGS Integration milestones throughout 2003 LGS AO on worlds largest optical telescope will become incredible tool for astronomy First operational LGS on an 8-10 m telescope,System Flow & Control,