Research On Improving The Demodulation Accuracy Of Fiber Grating Sensor

Fiber grating sensor can wave length code to the measured physical quantity.For the sensitivity, other sensors can’t compare with it. Now this sensortechnology has been applied to many engineering practices. In order to applyfiber grating system to engineering practice, the signal demodulation technologyis the key technology. Nowadays designing a fiber grating system with highresolution and low cost becomes one of the hot spots.In this paper, based on the theoretical of the matching demodulation method,I design a new type of the matching demodulation system of optical fiber Bragggrating sensor which bases on the piezoelectric ceramic. Then design apiezoelectric ceramic circuit which matched with this system, at the same time,in order to monitor the position of the piezoelectric ceramic, I design a devicewhich core is the photoelectric position sensitive devices with the function of themicro displacement amplification and detection. Put the displacement signalwhich is detected by the photoelectric position device as the feedback signal andput it effect on the micro displacement of the piezoelectric ceramic, then form aclosed-loop sensor with the functions of driving, testing, compensation anddemodulation.Calibrate the nonlinear of piezoelectric ceramic with the laser interferometer,and use the nonlinear to calibrate the best middle linear in experiment. Under thesame experiment condition, I finish the temperature sensing experiment with theopened-loop system or the closed-loop system. Analyzing the results, it can beseen that the index of the closed-loop sensing system is better than the opened-loop system. The closed-loop system effectively resolves the influence of thehysteresis nonlinearity and the creep character of the piezoelectric ceramic on the control accuracy of the micro displacement, and greatly improves themeasurement precision of the sensing system and the demodulation accuracy ofthe sensor demodulation system.