Research On Key Techniques Of Fiber Bragg Grating Humidity And Light Intensity Measurement

With the development of society,the demand for the precisely monitoring the meteorological environment become more and more urgent.The meteorological monitoring is closely related to the daily life of the people,and all kinds of sudden meteorological disasters are the main targets for our monitoring and prevention.In order to regulate meteorological work,prevent meteorological disasters and make rational use of meteorological as well as climatic resources,China promulgated the Meteorological Law of the People's Republic of China in 1999,which shows the seriousness and importance of meteorological monitoring work to some extent.Humidity and light intensity are two key indicators of meteorological monitoring information.Humidity refers to the amount of water vapor in the air,which reflects the degree of wetness of the air roughly.Light intensity refers to the amount of light or energy received per unit area.These two indicators occupy an very important position in the fields of agriculture,industry,medicine and energy.However,under the conditions of strong electromagnetic interference and severe weather,the traditional mechanical or electronic surveying equipment can hardly accomplish the measurement target.Benefit from the development of optical fiber sensing technology,making it possible for optical passive component to monitor the weather condition.Based on fiber grating sensing technology,this thesis has developed and designed a humidity and a light intensity sensor,these sensors with a better resistant to EMI and passive sensing characteristics.It has important practical application in the field of It has important practical value in the field of environmental monitoring such as transmission lines,bridges,tunnels and airports.In this paper,the fiber grating sensing mechanism is mainly used as an entry point.The main work and achievements are as follows:1.Analyzed the mainstream moisture-sensitive materials,combined with the principle of fiber grating,choosing polyimide as the humidity-sensitive material,and theoretically proved the feasibility of fiber grating coating humidity measurement scheme.2.Based on the polyimide coating process,making the humidity sensor and designing its external package structure.At the end of this paper,the calibration and testing environment was set up,to calibrate and test the sensors.From the test we could get the result that the fiber optic humidity sensor has a response time of 10 min,a humidity hysteresis of less than or equal to 4%RH and an error of less than or equal to 6%RH.3.Based on the output characteristics of solar panels,the paper proposes three schemes to convert the light intensity into temperature,stress and periodic changes in stress for measurement,and briefly describes the advantages and disadvantages of the three schemes,respectively.The innovation of this thesis lies in that through the motor speed measuring the light intensity indirectly,which can effectively avoid the problems of temperature compensation and sensor aging.4.Based on the scheme proposed in the 3rd point of the abstract,the thesis designs the cantilever beam and the sensor packaging work.After that the thesis set up a light intensity calibration and testing platform,carried out the calibration and test work.The light intensity sensor developed by the paper with a resolution of 4KLux,rtest error of ± 4Klux compared with the standard electronic illumination mete.