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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 559394.0, MPI für Astronomie / Publikationen_mpia
The fiber coupler subsystem of the future VLTI instrument GRAVITY
Authors:Pfuhl, O.; Eisenhauer, F.; Haug, M.; Thiel, M.; Kellner, S.; Amorim, A.; Brandner, W.; Berger, J. P.; Rousselet-Perraut, K.; Perrin, G. S.; Straubmeier, C.; Gillessen, S.; Bartko, H.; Gräter, A. P.
Publisher:SPIE
Place of Publication:Bellingham, Wash.
Date of Publication (YYYY-MM-DD):2010
Title of Proceedings:Optical and Infrared Interferometry II
Start Page:77342A-77342A
End Page:8
Title of Series:SPIE
Volume (in Series):7734
Name of Conference/Meeting:Optical and Infrared Interferometry II
Review Status:not specified
Audience:Experts Only
Abstract / Description:We present the Fiber Coupler subsystem of the future VLTI instrument GRAVITY. GRAVITY is specifically designed to deliver micro-arcsecond astrometry and deep interferometric imaging. The Fiber Coupler is designed to feed the light from a science and a reference object into single-mode fibers. The Fiber Coupler consists of four independent units. The units de-rotate the FoV. A motorized half-wave plate allows rotating the liner polarization axis. Each unit provides actuators for fast piston actuation, tip-tilt correction and pupil stabilization for one of the beams from four VLT telescopes. The actuators are operated in closed-loop. Together with a dedicated Laser Guiding System, this allows to stabilize the beams and maximize the coherently coupled light. The fast piston actuator provides the crucial fringe tracking capability at a bandwidth of >220Hz. A special roof prism design allows to either split the FoV or to serve as a 50/50 beam splitter without changing the optical path. This offers the possibility of on-axis as well as off-axis fringe tracking. The optical train consists solely of mirrors, which ensures an achromatic behavior and maximum throughput. The sophisticated optical design compensates for aberrations which are introduced by off-axis parabolic mirrors. This allows to achieve Strehl ratios of >95% across the FoV.
Comment of the Author/Creator:Date: 2010, July 1, 2010
External Publication Status:published
Document Type:Conference-Paper
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2010SPIE.7734E..70P [ID No:1]
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