Axial-resolution in depth from focus digital holography

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    Abstract

    We use digital holography to quantify surface topography of rough objects in full-field. We calculate the variance of the intensity image as a focus metric over a set of reconstruction distances for each pixel, which results in a focus metric curve. The distance where the variance peaks is an estimate for the depth. First we analyze the lateral resolution of this method using the Talbot effect and argue that sub-mm axial resolution is feasible. Then, using a Michelson setup without magnifying optics or lateral scanning we experimentally demonstrate that sub-mm FWHM width of the focus curve can be achieved. This is significantly better than what was previously reported using digital holography and could make this technique useful for characterising objects in art and machine vision.
    Original languageEnglish
    Title of host publicationDigital Optical Technologies 2017
    EditorsBernard C. Kress, Wolfgang Osten, H. Paul Urbach
    PublisherSPIE
    Number of pages7
    ISBN (Print)978-1-5106-1115-3
    DOIs
    Publication statusPublished - 2017
    EventSPIE Digital Optical Technologies 2017 - Internationales Congress Center Munich, Munich, Germany
    Duration: 25 Jun 201729 Jun 2017
    https://spie.org/about-spie/press-room/-spie-digital-optical-technologies-2017-news-and-photos

    Publication series

    NameProceedings of SPIE
    Volume10335
    ISSN (Electronic)1605-7422

    Conference

    ConferenceSPIE Digital Optical Technologies 2017
    CountryGermany
    CityMunich
    Period25/06/1729/06/17
    Internet address

    Keywords

    • Digital holography
    • metrology
    • Talbot effect
    • depth from focus

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