Study On Chirped Fiber Grating Strain Senor

Fiber optical grating sensor is one which is made based on Grating wavelength's sensitive to temperature and strain. In addition to traditional electric sensor's function, it also has the advantages of anti-electromagnetic interference, wide measurement range, largely dynamic range, and good stability. They are widely used in composite material and concrete to monitor their structures, and also used in the electric power industry, petroleum controlling, and chemical industry.Countering the disadvantages of FBG demodulation's high costing and slow speed, in this paper, CFG, mainly used in fiber optical dispersion compensation in the past, is used as strain sensor, and its reflection light intensity shows strain value. So decrease costing greatly. CFG's sampling frequency increases from FBG's 100Hz to 5kHz. Obtain some valuable conclusions.First of all, this paper introduces CFG's structure, principle, making methods, its application and the research situation in the world. Then analysis CFG sensor's characters about strain and temperature. Through analysising cantilever beam's strain, we obtain accurate location and direction where CFG is pasted. And determine the best pasting and fixation means.The paper did the thorough discussion on questions appearing in the CFG intensity sensor research. Include: in 0 - 20t scale, though CFG's reflection lightwave bandwidth is FBG's 10 times, the reflection lightwave displacement, which the strain causes, still is bigger than CFG's bandwidth. It causes that the relationship between CFG's reflection light intensity and strain surpasses the linearity range. By compensating, we can solve the problem. Because of the intensity demodulation, the environmental change inevitably influences the strain measurement accuracy. The paper carries on the systemic experiment and analyzes the influence factor. In the end, carry on the static and dynamic experiment for the CFG strain sensor. The result demonstrates: in a short time, for example 30 minutes, excluding the serious external interference, the CFG sensor's drifting is only 0.1%, and the static measurement precision can be 0.5%. In 15km/h, dynamic measurement precision is in 2%. What I did in the paper is as following:1. Participate in the CFG strain sensor's design and calibration experiment.2. Study different CFG pasting means' influence on the cantilever beam, and obtain the best solidification means.3. Design special apparatus, and solve CFG smooth pasting in cantilever beam's hole.4. Solve the linearity scope deficient question of CFG's light intensity and strain.The result indicates: the conception, based on the CFG strain sensor, is feasible, specially dynamic and instantaneous strain measurement, for example, vehicles dynamic weight measurement. It owns the good application prospect.