A novel interference transducer based on the measurement principle of multicore fiber interference for vibration measurement of a cantilever beam is designed in the paper. Twin-core fiber is special designed fiber, which contains a pair of parallel fiber core. Two paths integrated in one fiber not only greatly decreases sensor's volume, but also makes environment temperature effect approximately equal to each. A twin-core fiber which is pasted on the cantilever beam with epoxy resin is used as the sensing element. The twin-core fiber act as a two-beam in-fiber integrated interferometer that has a far-field interferometric fringe pattern which shift thereupon with the cantilever beam oscillates. CCD was used to measure the displacement of interferometer fringes instead of the traditional photodetector. The continuous capture of interference fringes was realized. The design of low pass filter and image smoothing were finished according to the characteristics of interference fringes. Orientation error of interference fringe center was removed. Displacement of fringe center was calculated and the spectrum of the displacement was analyzed with Fourier Transform. The system uses high-speed CCD camera as the photoelectric transformer. By using the high sensitivity twin-core fiber, the system realizes high precision measurement of vibration frequency, and ensures real-time performance. The experiment results show that the vibration measurement method is feasible and possesses potential application prospect in tiny vibration measure.

Date Published: 20 May 2009
PDF: 4 pages
Proc. SPIE 7283, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 72833N (20 May 2009); doi: 10.1117/12.828781

Published in SPIE Proceedings Vol. 7283:
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; James C. Wyant; Robert A. Smythe; Hexin Wang, Editor(s)