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Proceedings Paper

Study on fiber Bragg grating displacement sensing
Author(s): Li Li; Chun-feng Ge
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Paper Abstract

The paper proposes a novel demodulation method of fiber grating displacement sensing with applying dual grating structure. The linear tuning sensitive structure of isosceles triangle-shaped cantilever beam is designed which can be used to eliminate the influence from environmental temperature. The fiber grating is pasted in the cantilever top and under both sides. When the cantilever free end take place the displacement, this would generate strain which can make the gratings compression and tensile respectively, furthermore, cause the changes of Bragg grating reflection wavelength. The changes of grating is caused by temperature influence in the same direction, and caused by stress change in the opposite direction. Therefore, the change of optical power caused by temperature was offset, that is, eliminate the influence from environmental temperature. When the free end has displacement or load, the grating on beam top surface was stretched, Bragg wavelength drift to the long-wave direction, and the grating under the surface is compressed, which make wavelength drift to the short-wave direction. The changes of light intensity can be seen from the spectrogram. Using linear tuning properties without chirped of cantilever beam, micro-displacement in the free end can effective turned into the strain of equal intensity beam. The changes of Bragg wavelength caused by strain can be shown in optical power meter, and would be transformed into voltage display through demodulation system. Therefore, displacement sensing information is derived indirect; the optical measurement of micro-displacement is realized. The experiment result shows the system sensitivity is 0.87mV/μm, and displacement resolution is 2.12nm/mm.

Paper Details

Date Published: 24 August 2009
PDF: 6 pages
Proc. SPIE 7381, International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, 738121 (24 August 2009); doi: 10.1117/12.835023
Show Author Affiliations
Li Li, Tianjin Univ. of Technology (China)
Chun-feng Ge, Tianjin Univ. (China)


Published in SPIE Proceedings Vol. 7381:
International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors

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