Fiber modal noise mitigation by a rotating double scrambler

G. Raskin, D. Rogozin, T. Mladenov, C. Schwab, D. Coutts

    Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review


    Fiber modal noise is a performance limiting factor in high-precision radial velocity measurements with multi-mode fiber fed high-resolution spectrographs. Traditionally, modal noise is mitigated by agitating the fiber, this way redistributing the light that propagates in the fiber over many different modes. However, in case of fibers with only a limited number of modes, e.g. at near-infrared wavelengths or in adaptive-optics assisted systems, this method becomes very inefficient. The strong agitation that would be needed stresses the fiber and can lead to focal ratio degradation. As an alternative approach, we propose to use a classic optical double scrambler and to rotate the scrambler's first fiber end during each exposure. Because of the rotating illumination pattern of the scrambler's second fiber, the modes that are excited vary continuously. This leads to very efficient averaging of the modal pattern at the fiber exit and to a strong reduction of modal noise. In this contribution, we present a prototype design and first laboratory results of the rotating double scrambler.

    Original languageEnglish
    Title of host publicationAdvances in Optical Astronomical Instrumentation 2019
    EditorsSimon Ellis, Céline d'Orgeville
    Place of PublicationBellingham, Washington
    Number of pages2
    ISBN (Electronic)9781510631472
    ISBN (Print)9781510631465
    Publication statusPublished - 3 Jan 2020
    EventAdvances in Optical Astronomical Instrumentation 2019 - Melbourne, Australia
    Duration: 9 Dec 201912 Dec 2019

    Publication series

    NameProceedings of SPIE
    ISSN (Print)0277-786X
    ISSN (Electronic)1996-756X


    ConferenceAdvances in Optical Astronomical Instrumentation 2019


    • Modal noise
    • Optical fiber
    • Radial velocity
    • Spectrograph


    Dive into the research topics of 'Fiber modal noise mitigation by a rotating double scrambler'. Together they form a unique fingerprint.

    Cite this