Low-cost scheme for high-precision dual-wavelength laser metrology

Yitping Kok*, Michael J. Ireland, J. Gordon Robertson, Peter G. Tuthill, Benjamin A. Warrington, William J. Tango

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    6 Citations (Scopus)
    17 Downloads (Pure)


    A method capable of delivering relative optical path length metrology with nanometer precision is demonstrated. Unlike conventional dual-wavelength metrology, which employs heterodyne detection, the method developed in this work utilizes direct detection of interference fringes of two He-Ne lasers as well as a less precise stepper motor open-loop position control system to perform its measurement. Although the method may be applicable to a variety of circumstances, the specific application in which this metrology is essential is in an astrometric optical long baseline stellar interferometer dedicated to precise measurement of stellar positions. In our example application of this metrology to a narrow-angle astrometric interferometer, measurement of nanometer precision could be achieved without frequencystabilized lasers, although the use of such lasers would extend the range of optical path length the metrology can accurately measure. Implementation of the method requires very little additional optics or electronics, thus minimizing the cost and effort of implementation. Furthermore, the optical path traversed by the metrology lasers is identical to that of the starlight or science beams, even down to using the same photodetectors, thereby minimizing the noncommon path between metrology and science channels.

    Original languageEnglish
    Pages (from-to)2808-2814
    Number of pages7
    JournalApplied Optics
    Issue number12
    Publication statusPublished - 20 Apr 2013

    Bibliographical note

    This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ao/abstract.cfm?uri=ao-52-12-2808. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.


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