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Proceedings Paper

Superposition fringes for profiling applications
Author(s): J. Schwider
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Paper Abstract

Interferometric profilometers make use of two-beam interferometers with spectral broad band or more general polychromatic illumination either simultaneously or successively on the time axis. Since the criterion for a position of an object point on the z-axis is commonly the condition OPD = 0, the two-beam interferometer should allow for such an adjustment being a typical feature of Michelson- or Mirau-type instruments. However, the very simple Fizeau interferometer does not allow for this adjustment since it is a real wedge instrument. But it is well known that the superposition fringes between two interferometers in a series arrangement enable such an adjustment. In case of two two-beam interferometers in series arrangement a loss in contrast by a factor of at least 2 has to be tolerated. The combination of a multi-beam interferometer as a Fabry-Perot resonator with a Fizeau interferometer will deliver a fringe pattern which has a contrast of Rm where R is the reflectivity of the Fabry-Perot(FP)-plates and m is the ratio of the resonator lengths of the two interferometers in series. The disadvantage of the FP-solution is an intensity loss of the order (1-R)2. Here the occurrence of bright broad-band sources with transversal mono-mode character as superlum-diodes or fs-lasers opens up new perspectives. Fine tuning could be obtained either by mirror shifts or tilt of a FP-etalon.

Paper Details

Date Published: 18 June 2007
PDF: 11 pages
Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 661627 (18 June 2007); doi: 10.1117/12.725038
Show Author Affiliations
J. Schwider, Institute of Optics, Information and Photonics (Germany)


Published in SPIE Proceedings Vol. 6616:
Optical Measurement Systems for Industrial Inspection V
Wolfgang Osten; Christophe Gorecki; Erik L. Novak, Editor(s)

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