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Proceedings Paper

Optical fiber strain gauge using a mirror with a pinhole
Author(s): Toru Yoshizawa; Hiroshi Takase; Masayuki Yamamoto; Yukitoshi Otani
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Paper Abstract

In the conventional measurement of strain, resistance wire types of strain gauges have been used in most of cases. However, other kinds of strain gauges have been reported recently and optical fiber gauges appeared on the market. Here, instead of a conventional strain gauge made of a metal wire, we propose an optical fiber gauge. This gauge consists of two fibers for transmitting a beam from a light source and for receiving a reflecting-back beam, and in between them a concave mirror with a hole is settled. This mirror is used for transmission and partial reflection of the beam. When strain is given to the testing specimen to which the gauge is adhered, small displacement between two fiber ends is brought. The construction of this gauge is so sensitive to gap change between the fibers that high sensitivity is realized in measurement. In addition to high sensitivity, this gauge is featured by a small size and short gauge length. To verify this principle, experiments are repeated by using a thin plate specimen made of copper. The gauge is made of a plastic fiber of 0.5 mm in diameter and a small concave miro with a pinhole. Due to this mirror construction, the fluctuation of the beam intensity can be checked and the stable normalized output signal is obtained. Because the normalized signal is obtained form two signals; transmitted and reflected signals. An experimental result showed a high sensitivity in experimental measurement, and even for the intentional fluctuation of the beam intensity, we could get same measuring result in strain measurement.

Paper Details

Date Published: 26 November 2001
PDF: 6 pages
Proc. SPIE 4448, Optical Diagnostics for Fluids, Solids, and Combustion, (26 November 2001); doi: 10.1117/12.449364
Show Author Affiliations
Toru Yoshizawa, Tokyo Univ. of Agriculture and Technology (Japan)
Hiroshi Takase, Tokyo Univ. of Agriculture and Technology (Japan)
Masayuki Yamamoto, Tokyo Univ. of Agriculture and Technology (Japan)
Yukitoshi Otani, Tokyo Univ. of Agriculture and Technology (Japan)

Published in SPIE Proceedings Vol. 4448:
Optical Diagnostics for Fluids, Solids, and Combustion
Carolyn R. Mercer; Soyoung Stephen Cha; Gongxin Shen, Editor(s)

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