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Proceedings Paper

High numerical aperture multimode fibers for prime focus use
Author(s): Kaiyuan Zhang; Jessica R. Zheng; Will Saunders
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Paper Abstract

Modern telescopes typically have prime focus speeds too fast for direct use with standard numerical aperture (NA=0.22±0.02) silica-cored fibers. Specifically, the current design for the proposed Maunakea Spectroscopic Explorer (MSE) telescope is ~f/2, requiring fibers with NA>0.25. Micro foreoptics can be used to slow the beam, as used on the prime focus spectrograph (PFS) on Subaru, but this adds cost and complexity, and increases losses. An attractive alternative is offered by high NA pure silica-cored fibers, which can be used directly at f/2, and which are now available from multiple vendors. We present throughput and focal ratio degradation measurements on two samples of these high NA fibers. It is found that the measured attenuation losses are comparable with the best available standard NA fibers. The fibers were also tested for focal ratio degradation, and the fiber from CeramOptec was found to have acceptable FRD, representng additional collimator losses ~1%. The near field performance of the high NA fiber is also investigated and these high NA fibers exhibit very good scrambling performance; we saw no evidence for significant output near-field variations for varying input beam angles or position in a 50m fiber.

Paper Details

Date Published: 22 July 2016
PDF: 11 pages
Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 99125J (22 July 2016); doi: 10.1117/12.2232131
Show Author Affiliations
Kaiyuan Zhang, Australian Astronomical Observatory (Australia)
Nanjing Institute of Astronomical Optics & Technology (China)
Jessica R. Zheng, Australian Astronomical Observatory (Australia)
Will Saunders, Australian Astronomical Observatory (Australia)

Published in SPIE Proceedings Vol. 9912:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II
Ramón Navarro; James H. Burge, Editor(s)

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