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Proceedings Paper

Height profile measurement by means of white light interferometry
Author(s): Pavel Pavlicek
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Paper Abstract

White light interferometry is an established method for height profile measurement of objects. This method, unlike classical interferometry, can be used for measurement of objects with rough surface which is an important advantage. The white light interferometer is in principle a Michelson interferometer with a broad-band light source and a CCD camera as a detector. The Michelson interferometer has the object to be measured in one arm and the reference mirror in the other arm. Due to the reflection on the rough surface, a speckle pattern arises in the detector plane. This pattern is superimposed on the reference wave. The phase in particular speckle is random, but it remains approximately constant within one speckle. This renders the white light interference observable, if the optical path lengths of the two arms differ less than the coherence length. The object to be measured is mounted on a micropositioner for translating in the longitudinal direction. Gradually, as parts of the object surface cross the reference plane, the white light interference is observable in thc corresponding speckles. The position of the micropositioner in which the interference is maximal is stored for each pixel. This value for each pixel of the object image describes the geometrical shape of thc measured object. The measurement range is theoretically unlimited, practically it is limited by the range of the micropositioner. Thc longitudinal uncertainty does not depend on the parameters of the optical setup, its value is given by the roughness of the measured surface. The height profile of the object is measured during one measurement process, unlike the scanning profilers. The illumination and the observation are coaxial which avoids shadows.

Paper Details

Date Published: 21 November 2003
PDF: 6 pages
Proc. SPIE 5259, 13th Polish-Czech-Slovak Conference on Wave and Quantum Aspects of Contemporary Optics, (21 November 2003); doi: 10.1117/12.545112
Show Author Affiliations
Pavel Pavlicek, Palacky Univ. (Czech Republic)
Institute of Physics (Czech Republic)

Published in SPIE Proceedings Vol. 5259:
13th Polish-Czech-Slovak Conference on Wave and Quantum Aspects of Contemporary Optics
Jerzy Nowak; Marek Zajac; Jan Masajada, Editor(s)

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