Key Technology Of Fiber Bragg Grating Sensors Wavelength Detection

As a result of its characteristic of wavelength encoding and linear strain and temperature response, fiber grating has a broad application future in the field of optical sensing. But there are many practical problems to be resolved, and increasing the accuracy of wavelength detection is an important one.Modern digital signal processing technique is applied in fiber grating sensing and the scheme of signal processing of wavelength demodulation is optimized. The main research work is as follows:The theories and general situations correlative with fiber Bragg grating sensors are briefly introduced. And our wavelength demodulation system is presented.The affection of optical source on measurement accuracy of the system is discussed. The mechanism of the affection is simulated by constructing power model. The power normalizing scheme to resolve the problem is presented. The effectiveness is presented by the simulation results. At last, the effectiveness is proved by contrasting the wavelength curve when measuring the same static grating with temperature controlling. The wavelength varying range is reduced by 8pm.Spectrum rebuilding scheme, a wavelength detection scheme with high accuracy, is discussed. At first, physical mechanism of the interferometric noise is described. It is caused by the residual reflections occurring at various fiber terminations such as fiber joints. To resolve the problem, it is necessary to use a digital filter and choose a peak location algorithm with high accuracy. The spectrum rebuilding scheme based on digital low-pass filter and curve fitting is brought forward after riddling. Then the dealing process of spectrum rebuilding is simulated and the result is discussed. At last, the experiment result proved the effectiveness of the spectrum rebuilding technology. The experiment result show that the wavelength detection accuracy is improved by an order of magnitude using the spectrum rebuilding technology compared with that obtained from direct peak search.Some other schemes to enhance the accuracy are illustrated. Including enhancing signal...