Research On Fiber Optic Multi-point Distributed Temperature Strain Sensing Technology

Fiber optic distributed sensing has unique advantages in the field of health detection of large buildings such as bridges,dams,tunnels,etc,and has been widely concerned,and is a research hotspot in the field of fiber optic sensing.In this paper,a new white light interference sensing system based on single chip microcomputer is designed,which realizes multi-point distributed strain and temperature sensing and measurement.The main contents are as follows:(1)The optical fiber white light sensing principle,optical fiber temperature sensing principle and strain sensing principle of the optical fiber Michelson interferometer are described;The multi-point distributed sensing system based on fiber switch,fiber ring cavity and fiber F-P cavity demodulation and its sensing principle are discussed respectively.An improved Michelson interferometer sensing system is also introduced.This paper provides theoretical support for the experimental research of multi-point distributed temperature strain sensing based on Michelson interferometer.(2)A micro-displacement platform control system of white light interference sensing system based on single chip microcomputer is designed.Each module and basic function of STM32 single chip microcomputer are introduced.Automatic optical path matching and optical path detection are realized by means of galvanometer control and step displacement table driving.Finally,the integration of the control system is realized through system coordination.The system has the advantages of small volume,simple operation and easy to carry.(3)The temperature and strain response characteristics of a single point sensing system are experimentally studied.In the strain experiment,the optical path difference of the two arms is changed by changing the axial stress applied to the sensing fiber,and the corresponding relationship between the strain and the optical path difference is obtained.The measuring range of strain sensing is 217 με-1340 με,the sensitivity is 0.281 μm/με,and the linear fit is 0.998.In the temperature experiment,the optical path difference of the two arms is changed by changing the temperature of the sensing fiber,and the corresponding relationship between the temperature and the optical path difference is obtained.Temperature The temperature measurement range is 40℃-100℃,the sensitivity is 1.986μm/℃,and the linear fit is 0.993.(4)The sensing characteristics of the multi-point distributed sensing system based on fiber ring cavity demodulation and the improved Michelson interferometer multi-point distributed sensing system are experimentally studied.The equivalent optical path points of each sensor are scanned by the micro displacement control system to realize quasi-distributed temperature and strain sensing and measurement,and the displacement data is collected and processed by the serial debugging assistant.The work of this paper provides a reference for the design and application of white light interference sensing system.