Improved Thermal Fiber Grating Anemometer

Compared with traditional mechanical and electronic sensors,optical fiber sensors have many unique advantages,such as corrosion resistance,antielectromagnetic interference,compact structure and so on.In this paper,we combine optical fiber sensing technology with coating to carry out a anemometer based on fiber grating.The main contents are as follow:1.Development,sensing principle,application,common classification and main preparation methods of fiber grating are introduced,development and sensing principle of fiber Bragg grating anemometer are concluded,and the main research contents and significance of this paper are expounded.2.An fiber Bragg grating thermal anemometer based on graphene is proposed.Six layers of graphene are deposited on the polishing area by natural sedimentation.Graphene absorbs the pump light to generate heat,which changes the center wavelength of FBG,then measures the wind speed by wind tunnel experiment.In the experiment,airflow velocity can reach 0-20.41 m/s.When the wind speed is less than 6m/s,the sensitivity is 180.47pm/(m/s).3.An FBG thermal anemometer with silver film coated is proposed.The fiber grating area is polished to improve the sensitivity of the sensor,and the polished FBG is coated with a silver film with thickness of 100nm by vacuum evaporation.The input light is coupled from the fiber core to cladding by coupled structure,the silver film absorbs the pump light to generate heat.When wind passes through the surface,silver film is cooled down.By measuring the shift of the center wavelength of FBG,the wind speed can be calculated.In the experiment,airflow velocity can reach 0-20.362m/s.When the wind speed is less than 6m/s,the sensitivity is 339.83pm/(m/s)and the resolution is 0.06m/s.