High Precision And High Resolution Fabry Perot Temperature Sensor

With the gradual maturity of optoelectronic devices and the continuous promotion of engineering needs,optical fiber F-P(Fabry Perot)optical fiber sensor is considered to have a wide application prospect in temperature measurement because of its simple structure,small volume,corrosion resistance and high sensitivity.At present,there is a problem that high-resolution measurement cannot be realized in harsh environment(such as ocean,etc.).The temperature resolution of optical fiber F-P temperature sensor working normally under harsh conditions is not high.This thesis starts with the design and demodulation of optical fiber F-P temperature sensor,and finally realizes the high-resolution measurement of optical fiber F-P temperature sensor.1.The research status of optical fiber temperature sensing technology and optical fiber F-P temperature sensor technology are summarized.2.The theoretical working principle and structure classification of optical fiber F-P temperature sensor are summarized,the theoretical model of F-P interference considering the divergence of transmission beam in space is established,and the influence of the divergence of transmission beam in space on the spectral characteristics of F-P sensor is simulated.3.The spectrum fitting algorithm and cavity length demodulation algorithm of F-P temperature sensor are summarized.Aiming at the poor temperature resolution of the current algorithm,the composite single multimodal algorithm and wavelength moving average single multimodal algorithm are proposed,and the related algorithms are analyzed theoretically.4.Aiming at the problem of increasing the number of interference fringes and poor contrast of optical fiber F-P temperature sensor made of ordinary single-mode optical fiber,it is proposed to use tec(thermal expansion core)optical fiber as the manufacturing material of optical fiber F-P temperature sensor,which improves the contrast of the sensor under high interference fringes density and provides support for improving the resolution through multimodal demodulation.5.The temperature sensitivity,linearity,repeatability,resolution and response time of the sensor samples were experimentally studied.The experimental results obtained are as follows.It is experimentally measured that the temperature of the sensor has a cavity length sensitivity of 79.074 nm/℃in the temperature range of10℃～100℃,and the linearity R~2 can reach 0.999999(nine decimal places).The sensor has a cavity length sensitivity of 79.085 nm/℃under temperature,and the linearity R~2 can reach 0.999999(nine digits after the decimal point).The repeatability of the sensor is about 0.05℃,and the best temperature resolution can be obtained by sliding single multimodal algorithm,which is about 0.000051℃.Experiments show that the optical fiber F-P temperature sensor made of Tec optical fiber has good repeatability and high resolution.The high-resolution temperature sensor developed in this thesis has reached the advanced level at home and abroad in the temperature resolution measurement of optical fiber F-P sensor(the temperature resolution of SBE56 temperature sensor for ocean temperature measurement of American seabird company is 0.0001℃).