The Measurements of Dynamics Responses by Power Modulated Fiber Gratting Sensors
Date Issued
2004
Date
2004
Author(s)
Hsu, Shuo-Hsiu
DOI
zh-TW
Abstract
The application of fiber gratings on strain sensing system has the advantages of electromagnetic immunity and high sensitivity. However, the capability on the measurement of dynamic response is still questionable. The main problem is the speed and accuracy of reading fiber gratings’ signal. The power modulated fiber grating measurement system uses fiber Bragg gratings for strain sensing, and its power is modulated by long period fiber gratings to obtain the signals’ changes after stresses are applied. It has some advantages such as high reaction speed and resolutions with a simple setup. The main objective of this thesis is to establish a new power modulated fiber grating sensor system and make improvements on the accuracy of strain measurement. Another four measurement techniques, which include the laser Doppler vibrometer, the laser optical displacement sensor, strain gauges and the impedance analyzer, are used to verify the results obtained by fiber grating sensors. In addition to qualitative analysis, we also provide a method to make quantitative determination of dynamic displacements. To improve the practicability of the fiber grating sensing system, the wavelength division multiplexing system is also used in this study.
The experiments started with measurements on static systems and proceeded to steady systems. The highest frequency that the fiber grating sensing system can be achieved is about 160000 Hz. Finally, the transient responses of a beam, a plate and a solid block are investigated and are discussed in detail.
Subjects
光纖光柵
能量調變
布拉格光纖光柵
長週期式光纖光柵
fiber
power modulated
fiber grating sensor
Type
thesis
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