An efficient, compact, and versatile fiber double scrambler for high precision radial velocity instruments

Samuel Halverson, Arpita Roy, Suvrath Mahadevan, Lawrence Ramsey, Eric Levi, Christian Schwab, Fred Hearty, Nick Macdonald

Research output: Contribution to journalArticleResearchpeer-review

Abstract

We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variations and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87% using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.

LanguageEnglish
Article number61
Pages1-9
Number of pages9
JournalAstrophysical Journal
Volume806
Issue number1
DOIs
Publication statusPublished - 10 Jun 2015
Externally publishedYes

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radial velocity
fibers
spectrographs
lenses
illumination
fibre
pupils
far fields
balls
planets
near fields
train
optical fibers
near infrared
alignment
prototypes
telescopes
optics
planet
glass

Keywords

  • instrumentation: spectrographs
  • techniques: radial velocities
  • techniques: spectroscopic

Cite this

Halverson, Samuel ; Roy, Arpita ; Mahadevan, Suvrath ; Ramsey, Lawrence ; Levi, Eric ; Schwab, Christian ; Hearty, Fred ; Macdonald, Nick. / An efficient, compact, and versatile fiber double scrambler for high precision radial velocity instruments. In: Astrophysical Journal. 2015 ; Vol. 806, No. 1. pp. 1-9.
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abstract = "We present the design and test results of a compact optical fiber double-scrambler for high-resolution Doppler radial velocity instruments. This device consists of a single optic: a high-index n ∼ 2 ball lens that exchanges the near and far fields between two fibers. When used in conjunction with octagonal fibers, this device yields very high scrambling gains (SGs) and greatly desensitizes the fiber output from any input illumination variations, thereby stabilizing the instrument profile of the spectrograph and improving the Doppler measurement precision. The system is also highly insensitive to input pupil variations, isolating the spectrograph from telescope illumination variations and seeing changes. By selecting the appropriate glass and lens diameter the highest efficiency is achieved when the fibers are practically in contact with the lens surface, greatly simplifying the alignment process when compared to classical double-scrambler systems. This prototype double-scrambler has demonstrated significant performance gains over previous systems, achieving SGs in excess of 10,000 with a throughput of ∼87{\%} using uncoated Polymicro octagonal fibers. Adding a circular fiber to the fiber train further increases the SG to >20,000, limited by laboratory measurement error. While this fiber system is designed for the Habitable-zone Planet Finder spectrograph, it is more generally applicable to other instruments in the visible and near-infrared. Given the simplicity and low cost, this fiber scrambler could also easily be multiplexed for large multi-object instruments.",
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Halverson, S, Roy, A, Mahadevan, S, Ramsey, L, Levi, E, Schwab, C, Hearty, F & Macdonald, N 2015, 'An efficient, compact, and versatile fiber double scrambler for high precision radial velocity instruments', Astrophysical Journal, vol. 806, no. 1, 61, pp. 1-9. https://doi.org/10.1088/0004-637X/806/1/61

An efficient, compact, and versatile fiber double scrambler for high precision radial velocity instruments. / Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath; Ramsey, Lawrence; Levi, Eric; Schwab, Christian; Hearty, Fred; Macdonald, Nick.

In: Astrophysical Journal, Vol. 806, No. 1, 61, 10.06.2015, p. 1-9.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Ramsey, Lawrence

AU - Levi, Eric

AU - Schwab, Christian

AU - Hearty, Fred

AU - Macdonald, Nick

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