| Temperature is a physical quantity which to characterize the degree of hot and cold about an object, it is one of the most important measurement of physical quantities in industrial, medical, scientific and other fields, and also is the key link in the production of industrial automation. With thermistor, thermocouples and other electrical signal as a working basis, the temperature sensor has played a major role in the national economy, scientific research, national defense and space technology. However, this method is susceptible to electromagnetic interference, radiation and a variety of shortcomings. Especially in some certain areas (such as industrial production, petrochemical, power, medicine, etc.), Traditional electric sensing method of temperature measurement is severely restricted in inflammable and explosive environment or which is susceptible to electromagnetic interference. With the rapid development of optical fiber manufacturing technology, optical fiber sensing technology, signal analysis and processing technology, the fiber optic temperature measurement method has gradually developed into a new type of temperature measurement technology.GaAs-based edge wavelength absorption spectrum with increasing temperature drift characteristics of the long-wavelength direction, we propose a system applicable to the temperature spectrum demodulation data processing method that eliminates background noise spectrum, eliminating the spectral analysis Miriam dark current shot noise, reset noise, amplifier noise, and background noise consisting of light shot noise. This method is based on the wavelength spectrum modulation demodulation temperature information, to avoid measurement errors caused by changes in the intensity measurement system, and design experiments to further verify the reasonableness of the demodulation method. This method uses a query table proofread way to get the temperature value, can reduce the amount of data measurement system operation, reducing power consumption measurement system control unit, the temperature increase speed. The results showed that in the range of 25℃-70℃, the measurement accuracy is less than ±0.1 ℃; in the range of 70℃-250℃, the measurement accuracy is less than ±0.7℃. Experimental results show that the demodulation method meets the measurement system needs of high precision and small computation, and we has applied for national patent.Finally, in order to verify the self-calibration function of the temperature measurement system designed in the paper, this paper design respectively self-calibration waveform comparison test and spectral analysis device comparison test. Experimental results show that when light intensity of the measurement system changes or at different ambient temperatures, waveform self-calibration function in the measurement system can effectively solve the interference problem described above; when ambient temperature of spectrometer changes, the temperature measurement system which has a spectral self-calibration function can effectively eliminate spectrometer wavelength shift caused by the changing of temperature, get a smaller system temperature measurement error and higher accuracy.Experimental results show that the performance of multi-channel self-calibration optical fiber temperature measurement system based on the absorption of GaAs is very good. This design can promote the use of temperature measurement system in refineries, gas stations, oil depots and other flammable environment. Besides, this system is also applicable to industrial microwave heating in the microwave, microwave chemistry, large motor stator, bearing and other equipment as well as the medical industries RF, microwave apparatus, magnetic resonance imaging and other instrument temperature monitoring. |
PDF Full Text Request