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Proceedings Paper

Three-dimensional step-height measurement using Mirau-type spectral interference microscope with acousto-optic tunable filter as frequency scanning device
Author(s): Dalip Singh Mehta; Shohei Saito; Hideki Hinosugi; Mitsuo Takeda; Takashi Kurokawa
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Paper Abstract

We propose a non-mechanical scanning Mirau-type spectral interference microscopic imaging system for the measurement of three-dimensional step-height of discontinuous objects. In this system a superluminescent diode is used as a broad- band light source, and an acousto-optic tunable filter (AOTF) as a high-resolution frequency scanning device. The interferometric system was made unbalanced by putting the reference mirror position exactly half-way between the top and bottom of the total step-height of the discontinuous object. While scanning the frequency of the broad-band light source using AOTF, the interference fringes move in opposite directions on the top and bottom of the object, respectively. A two-dimensional Fourier transform method was used for the unique determination of the sign of fringe movement over a large area of the object without any photo- detectors and fringe counters. From the detected sign of the fringe movement and phase information, the three-dimensional step-height is measured. Experimental results of the measurement of 100 μm step-height are presented. The main advantages of the proposed system are non-mechanical scanning and large measurement range without ambiguity in the sign of phase.

Paper Details

Date Published: 20 June 2002
PDF: 10 pages
Proc. SPIE 4777, Interferometry XI: Techniques and Analysis, (20 June 2002); doi: 10.1117/12.472218
Show Author Affiliations
Dalip Singh Mehta, Univ. of Electro-Communications (Japan)
Shohei Saito, Univ. of Electro-Communications (Japan)
Hideki Hinosugi, Univ. of Electro-Communications (Japan)
Mitsuo Takeda, Univ. of Electro-Communications (Japan)
Takashi Kurokawa, Tokyo Univ. of Agriculture and Technology (Japan)

Published in SPIE Proceedings Vol. 4777:
Interferometry XI: Techniques and Analysis
Katherine Creath; Joanna Schmit, Editor(s)

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