Study On Non-Scanning Correlative Demodulation System Of Optical Fiber Fabry-Perot Sensor

Contrasting to other optic fiber sensors, with the advantages of compactness, sensitivity, stability and interference-free with electro-magnetic field, optic fiber Fabry-Perot sensor is one of the optic fiber sensors which is utilized in engineering firstly, and capable of remote signals processing and multiplexing. However, the early applicable demodulation systems are either low precision or high cost, and the non-scanning correlation demodulation system is gradually coming into the research focus for the low cost and high precision. The foreign fellows have done a good work in non-scanning correlation demodulation system research, but the relating technology is monopolized and sold with high price. Corresponding, it is significant to develop a non-scanning correlation demodulation system with low cost and high precision.Firstly, the principle of optic fiber Fabry-Perot sensor non-scanning correlation demodulation system is analyzed; the theoretical correctness of demodulating optic fiber Fabry-Perot sensor with optic wedge is validated; and the conclusion is drawn that when the sensor cavity length is more than 2μm, the optic wedge can be utilized in optic fiber Fabry-Perot sensor cavity length demodulation.Secondly, the optic design, circuit design and software development of non-scanning correlation demodulation system is carried out. Optic design includes optic system optimization, parameters determination of optic parts and the adjustment of optic parts; the optic wedge cohering, optic path minimization and the cassette design are emphasized. Circuit design includes the signal processing of the CCD array output signal to obtain high resolution of demodulation system. The circuits of CCD driver signal conditioning, data acquisition and serial communication are implemented. The software design includes CCD driver signal, data acquisition design and field monitoring software.Lastly, the calibration experiment of demodulation system is carried out, and the continuous stretching and unloading experiments of sensors with different cavity length. The results shown that the demodulation system can reach the demodulation precision of 0.1 μm, the correlation coefficient is larger than 0.99, and the cost of demodulayion system is very cheap.The low cost and high precision requirement are implemented.