Study On The Application Of High Temperature Optical Fiber Micro-cavity Strain Sensor And Its Multiplexing

The optical fiber sensing technology is a new sensor technology rising in 20 th century. It has great differences with the traditional electrical sensor in terms of the sensing mode, sensing principle and signal detection and processing and so on. It is to perceive the changes of measured signal by detecting the light characteristics transmitting in the optical fiber.Multi-point high temperature strain testing is a key technology needed in the strain measurement. In recent years, people pay more and more attention on it and it has been widely used to real-time monitoring the LCD furnace wall 、 thermal mechanical deformation and other harsh environments. There are many research institutions which have done a lot of research on the optical fiber sensor. However, the optical fiber sensor which used in the high-precision measurement environment(such as high temperature, small space, high sensitivity and so on) is not yet mature. In this paper, we conduct a number of experiments and applied research based on this question. The method to manufacture the high temnperature optical fiber micro-cavity strain sensor to testing the strain using the 157 nm laser is proposed. And we use the tree multiplexing method to complish the multi-point testing. The main contents and results are as follows:(1) Using 157 nm laser machining system to produce high-temperature fiber Fabry-Perot strain sensing head, and then the relationship between the Fabry-Perot cavity length and strain is given.(2) We product many experimental testing on the sensor made by the above described method. First, all the factors influence the properties of the sensor from the aspect of the paste process of optical fiber sensor is introduced. The best way to paste is obtained by analyzing the experimental results, and then we discuss the various technical indicators of the sensor, such as zero drift, creep, temperature characteristics, repeatability and so on. Finally 3 compensation methods are proposed to use to solve the problem of mutual interference between thermal strain and force strain in the testing. And we analyze the advantages and disadvantages of each through experimental verification.(3) For the multi-point testing, a novel mutiplexing method is proposed. We build the experimental system and do a lot of experiments to verify the reliability of themethod. Problems and improvements found in the experiments is discussed.This thesis is basically completed the high temperature strain measurement experiments for high-precision environment. We get a kind of sensor which has more advantages than traditional sensor, such as small zero drift, a little creep, better repeatability, high sensitivity and is suitable for high temperature measurement. And we achieve the the spectrum acquisition under the multi-point measurement circumstances. In a word, we made some achievements, but the problems in the experiment need to be further studied and solved.