WHITE-LIGHT OPTICAL PROFILER WITH INTEGRATED PRIMARY STANDARD

Erik Novak, Joanna Schmit

Abstract

White light interferometry has become a common tool for measuring surfaces with large height ranges, slopes, and large roughness. The object is generally scanned through focus, varying the optical path difference between the light reflected from the object and from a secondary reference surface. The quality of the measurement is dependent on having a known and constant- velocity scan, as well as knowing the effective wavelength of the white light source at all times. In this paper we present a white light interferometer with an embedded second interferometer utilising a HeNe laser which provides an interferometric reference signal. This signal, based on the primary standard of the HeNe wavelength is used to monitor the scan and use the known scan positions in the height calculation algorithms. This yields improvements in the accuracy, and repeatability of topography measurements, allowing higher scan speeds without loss of data integrity.

Keywords

interferometer, surface metrology, profilometry, coherence scanning

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PWC-2003-TC2-009.pdf

DOI

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IMEKO TC

TC2 - Photonics

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