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8 August 2001 Vibration sensing with fiber Bragg grating
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Proceedings Volume 4513, Optoelectronic Information Systems and Processing; (2001)
Event: Optoelectronic Information Systems and Processing, 2000, Vladivostok, Russian Federation
The intensity of laser light is modulated when reflecting back from a fiber Bragg grating (FBG) which is glued onto a PZT vibrator and expands/contracts as the vibrator vibrates. The wavelength of the laser light is tuned to the slope of the FBG reflectance curve as a function of optical wavelength. Measuring the modulation component of the detected signal, we can directly observe mechanical vibration of the vibrator. The output of the sensor is stable and the involved harmonic component is below the system noise level. It is then believed that the sensor operation is linear. The sensitivity depends on the slope of the FBG reflection spectrum curve at the operating wavelength and is higher for the larger slope. The minimum amplitude of the vibrator measured in the experiment is 4.5 nm, which corresponds to the strain of 2.14 μstrain. Since not only an FBG has little influence on the object under measurement because of its small size and light weight but also its frequency characteristics are thought to be better than a PZT vibration sensor, i.e., the sensor can be used in a wide range of vibration frequency, an FBG is expected to provide us with an important tool of practicality for measuring mechanical vibration.
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Nobuaki Takahashi, Kazuto Yoshimura, and Sumio Takahashi "Vibration sensing with fiber Bragg grating", Proc. SPIE 4513, Optoelectronic Information Systems and Processing, (8 August 2001);

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