Research of double matched fiber optical grating demodulation system

摘要

In this paper, a design of demodulation system applied to Fiber Bragg Grating sensor will be illustrated. This system isbased on the principle of Fiber Bragg Grating strain sensing; therefore this applied system has the followingcharacteristics: high sensitivity, high precision, low cost and so on. Demodulation system bases on the traditional matching method, and uses the two matched Fiber Bragg Grating parallelmode. Just because of this, it improves on a certain extent compared with the traditional one. The two Fiber BraggGratings are pasted on Hollow Aluminum Cantilever respectively so as to realize the high precision and the large scalestrain demodulation. This paper proves the following theory through the academic analyses and experimentation, that is: pasting Fiber BraggGrating on Hollow Aluminum Cantilever can improve the response sensitivity. During the process of matching,increasing the load on the Hollow Aluminum Cantilever, when the qualities of load cannot beyond the limited quality,there is a good linearity relation between the change of load's quality and the change of wavelength. The limited qualitycomes from the experimentation. The experimentation proves that the structure of two matched Fiber Bragg Gratingparallel can increase the range of strain which can be measured largely, and at the same time this structure can solvedouble-value problem which exists in the ordinary matching method. The strain sense signal through the two paralleldemodulation Fiber Bragg Gratings into data processing circuit. The single chip processes the data from the dataprocessing circuit and works out the strain which is detected by Fiber Bragg Grating sensor.