A compact ESPI system for displacement measurements of specular reflecting or optical rough surfaces

R.S. Hansen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A stable and compact speckle interferometer for doing out-of-plane displacement measurements on reflective as well as diffusely scattering object surfaces is demonstrated. The set-up is based on a nearly path length compensated interferometer of the Fizeau type and uses diffuse illumination of the object combined with a speckled reference wave. This combination eliminates the need for special optical components, and the interferometer can be built of commonly available components. The diffuse illumination wave is obtained by scattering coherent light from a diffusely scattering surface. The speckled reference wave is established by reflecting a part of the diffuse illumination wave from a glass plate placed in front of the object. Besides relaxing the alignment tolerances of the set-up, the diffuse illumination eliminates the need for any preparation of the surface under test, which turns the system into a candidate for testing micro mechanical systems. When using the interferometer for measurements of the eye, the risk of focusing the laser beam on the retina is decreased due to the diffuse object illumination. (C) 2002 Elsevier Science Ltd. All rights reserved.
    Original languageEnglish
    JournalOptics and Lasers in Engineering
    Volume41
    Issue number1
    Pages (from-to)73-80
    ISSN0143-8166
    DOIs
    Publication statusPublished - Jan 2004

    Keywords

    • speckle interferometry
    • ESPI
    • specular surface
    • diffuse illumination
    • eye deformation
    • MEMS displacements measurements
    • vibration
    • contouring

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