Design And Experimental Research Of FBG Temperature Measurement System Based On DSP

Fiber Bragg Grating (FBG) is one of the most promising and the most representative optical fiber passive components. FBG has the potential to be widely used as sensors in more and more applications, for its advantages, such as high reliability, high sensitivity, anti-electromagnetic interference, corrosion, etc.Temperature is a very important parameter in industrial production needs consanguineous attention, but now many places, such as pressure, magnetic environment, the traditional sensor can not be used for measure temperature. But the FBG temperature sensor has security, anti-electromagnetic interference and strong unique advantages, so it is applied to temperature detection in specific areas is very imporent.The technology of FBG temperature sensor packaging has matured, but demodulation technology is important and difficult in the current field of optical fiber Bragg grating. Especially with the FBG sensing technology develop rapidly in domestic and foreign, the demodulation technology needs increasing urgently. There are several demodulation methods at this stage, many foreign institutions have research the fiber grating interrogation technique for long times and develop corresponding demodulation apparatus for industrial, but because of expensive, higher limits on the environmental requirements confine the further application of this technology. Currently many departments and research are in-depth studing, but most are in the experimental stage, and there are lang time to the standard and product.This thesis colligate considers the complexity, demodulation speed, precision and cost of fiber grating demodulation system, designs of a DSP-based temperature sensing FBG demodulation system. This system uses wavelength Pumped Multiplexing (WPM), which is pumped by wavelength division multiplexer, as the demodulation filter part. The relation between different sensor FBG wavelength and output power is distinguished, using WPM at different wavelengths Department insertion loss differences. And the signal can be demodulated. In the demodulation part, double optical structure is used, and a symmetrical dual-channel signal data integration program is proposed. Using these technologies, the drift, cased by light source and the optical intensity fluctuations is eliminated.DSP is a high-speed, high-precision tool for signal process. In the thesis, a DSP chip, model DSP2407 is chosen, for signal amplification, filtering, collecting, temperature conversion and data transmission functions. In the upper computer, software Labview is used to achieving data analyze, display and storage.It is worth mentioning that in the process of system design and experiments, digital potentiometer is used to control the amplifier. Meanwhile, a digital thermometer is used to comparing with this new temperature measurement system.The system stability and accuracy is proved by a large number of experiments. The result shows that the sensitivity of the DSP-based FBG temperature demodulation system is within 1℃, and the system has the characteristics of fast-response and reliable performance. This system is expected to be widely used in engineering applications.