Research On The Reflective Intensity Modulated Fiber Optic Accelerometer

A reflective intensity modulated fiber optic sensor is designed. It can be applied in the measurement of low frequency vibration acceleration.The configuration is compact and delicate for one single module fiber being used to send and receive.Its mathematic former is brief for certain conditions and ranges. By means of number and linearization processing, a real-time and undistorted low frequency vibration acceleration signal can be given out. The characteristic of the sensor is undistorted and unsensible to static drift of the initial distance.The global development of the optic fiber sensor and accelerometer is explained firstly, it is proved that optic fiber sensor has been a hot study focus in many scientists' eyes.In second part of this paper,base theory of the fiber optic accelerometer is presented in details, according to the principle of reflective intensity modulations new experimental scheme is described. The paper analyzes in detail the mechanics and optics theory.In the light of the characteristic of the intensity modulation optical fiber sensor, the theoretical analysis shows that the relation between the light intensity and displacement can be indicated by the same expression, though models of the fiber-optic intensity distribution at launching fiber end are different, such as Gaussian distribution, uniform distribution and those midst the upper two.The reference-way is presented, when the factors of the second order mechanics model are proper, the relative displacement, body to shell, is linear to the acceleration of shell.So the acceleration of the second order system is measured by measuring the relative displacement with the optical reflection displacement theory.In other parts of this paper, the design of the system is described in detail, including the selection of system device, the design of systematic circuit and software. In the hardware design, a single chip computer is used to acquired andprocess the data.Using 12 bits'A/D and D/A converter renders certain the system's measurement precision. The software's design uses modular method to accomplish the system's functions,including data input, storage, manage,output etc.