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Proceedings Paper

Sinusoidal wavelength-scanning interferometric reflectometry
Author(s): Osami Sasaki; Tomokazu Kuwahara; Ryohta Hara; Takamasa Suzuki
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Paper Abstract

We propose an interferometric reflectometry using a sinusoidal wavelength-scanning tunable laser diode to detect positions and profiles of multiple reflecting surfaces. An objective signal extracted from an interference signal contains the modulation amplitude Z and the phase (alpha) which are related to positions and profiles of multiple reflecting surfaces, respectively. By using values of the object signal at special times, we can produce an image intensity which shows where the reflecting surfaces exist. To obtain exact values of Z or values of (alpha) the objective signal is estimated with a conjugate gradient method. Experiments results show that a resolution of two-optical path difference (OPD) in the image intensity is 87 micrometer, and a final OPD accuracy is 2 micrometer and 8 micrometer for the two and three reflecting surfaces, respectively, in the case of the wavelength-scanning width of 7 nm. Profiles of front and rear surfaces of a silica glass plate with thickness of 20 micrometer are measured with an accuracy of about 10 nm.

Paper Details

Date Published: 7 May 1999
PDF: 4 pages
Proc. SPIE 3740, Optical Engineering for Sensing and Nanotechnology (ICOSN '99), (7 May 1999); doi: 10.1117/12.347759
Show Author Affiliations
Osami Sasaki, Niigata Univ. (Japan)
Tomokazu Kuwahara, Niigata Univ. (Japan)
Ryohta Hara, Niigata Univ. (Japan)
Takamasa Suzuki, Niigata Univ. (Japan)

Published in SPIE Proceedings Vol. 3740:
Optical Engineering for Sensing and Nanotechnology (ICOSN '99)
Ichirou Yamaguchi, Editor(s)

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