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Research On Sensitization And Multi-Point Detection Of Temperature Sensor Based On Fiber Fabry-Perot Interferometer

Posted on:2020-10-06Degree:MasterType:Thesis
Country:ChinaCandidate:J ZhangFull Text:PDF
GTID:2428330599959658Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Temperature sensing has extensive research and application value in industrial production,aerospace,medical and health,food processing and other industries.Traditional electric sensors are generally single-point measurements and don't function properly in harsh electromagnetic disturbances.Fiber optic sensors are receiving more and more attention due to their high sensitivity,strong anti-interference ability,and easy to be multiplexed.This paper will combine the advantages of fiber-optic sensors to design a temperature sensor based on Fabry-Perot Interferometer(FPI)structure,which will focus on increasing sensitivity and achieving multiplexing.The main research contents are as follows:(1)The principle of FPI is deduced,and the reflection spectrum of low-fitness FPI is analyzed in detail.The influence of cavity length and end face reflectivity on interference spectrum is discussed.A low-fitness FPI structure temperature sensor based on single-mode fiber(SMF)end face and UV-cured adhesive end face is proposed.The test of temperature between 20?~24? is carried out.The sensor achieves a sensitivity of up to-2.88nm/? and has excellent linearity by spectrum demodulation due to the large thermal expansion coefficient of UV-cured adhesive.(2)The venier effect is introduced to sensitize the FPI temperature sensor.The principle of generating the vernier spectrum by two cascaded FPIs and the amplification factor of the vernier effect on sensitivity are deduced in detail.A reference FPI interferometer is constructed by fusing the SMF with the fused silica capillary,and cascading with the prepared sensing interferometer to generate vernier effect.The external temperature can be demodulated by fitting the lower envelope of the vernier spectrum and tracking the wavelength corresponding to its minimum value.In the experiment of temperature sensing between 20?~24?,according to the difference of the cavity length difference of the two FPIs,the super sensitivity of 33.06nm/?,-58.60nm/?,67.35nm/? are achieved,respectively,which matches well with theoretical prediction.(3)The accurate recognition algorithm of wavenumber spectrum main frequency is proposed to demodulate the low-fitness FPI cavity length.The algorithm is based on Rife algorithm and has high estimation accuracy.Applying this algorithm to the FPI temperature sensor can significantly increase the temperature detection range.In addition,the algorithm is also applied to the parallel multiplexing of FPI sensing units.Under the experimental conditions,the crosstalk-free temperature sensing is successfully realized.Based on this,a three-dimensional multiplexing network of FPI sensors is proposed.
Keywords/Search Tags:fiber sensing, temperature sensor, Fabry-Perot interferometer, vernier effect, frequency recognition algorithm, sensors multiplexing
PDF Full Text Request
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