Study On The Properties Of Optical Fiber Fabry-perot Strain Sensor And Its Multiplexing

High-speed aircrafts need precise test of the strain in complex environment such as high temperature and narrow space, so features of the strain under high temperature for fiber F-P sensors are studied in this paper. A new multiplexing scheme based on serial multiplexing is proposed as well. The main contents are shown as follows:(1)In order to determine the attachment technology of fiber F-P sensors for measuring the strain, the software of finite element analysis called ABAQUS is used to model and simulate strain distribution, linearity and sensitivity of the sensors with different attachment technology and cavity size. From the result, it shows that two points attachment method of the fiber F-P sensors directly on the substrate can be used to achieve a better result for strain measurement.(2) The strain loaded response and temperature response of the fiber sensors attached cantilever beam are studied. It is proved that two points attachment method of the fiber F-P sensors have advantages over one point attachment method comparing the sensitivity and linearity. The creep, repeatability, thermal characteristics have also been tested. Two methods based on thermal characteristics for separating the thermal strain from the loaded strain are proposed: the first one is putting a FBG thermal sensor close to fiber F-P sensors for temperature compensation; the second one is solving equation of dual parameter of two sensors attached on opposing sides.(3)A serial multiplexing system for fiber F-P sensors is proposed in this paper. The feasibility of the system used for serial multiplexing is analyzed through recovering spectrum for serial multiplexed F-P sensors and polynomial fitting for a single sensor.Then the wavelength shift caused by the strain of the fiber sensors attached on the cantilever beam is fitted by utilizing serial F-P sensors.The performance of fiber F-P sensors for measuring the strain under high temperature are proved by both simulation and test. The serial multiplexing system for fiber F-P sensors can be applied for measuring strain at multiple spots when it does not need high precision.