Research On FBG Vibration Sensor With Double Semicircle Structure And Its Application In Stability Of OCT System

Optical coherence tomography is a new type of optical imaging technology which combines the principle of interferometer with confocal scanning. It makes use of the low coherence of broadband light source, by measuring the interference signal of the backscattering light and reference light. It obtains samples of internal microstructure through the digital processing. OCT not only is used in biomedical fields, but also is one of the nondestructive testing methods of cultural relics’surface microstructure. According to a study of the OCT technology used in colored paintings of historical relics, slight vibration of system relative to the sample will change the optical phase and decline the interference fringes which will cause the imaging quality. So, it’s necessary to design a vibration sensor which can be used in the OCT system for stability monitoring.Main research content of this paper:1 Establishing the mechanical model of vibration sensors, combined with the optical sensing theory of fiber Bragg grating, analyzed the design principle of fiber Bragg grating vibration sensor; 2)A compact fiber Bragg grating accelerometer based on an organic double-semicircle cantilever is proposed and experimentally demonstrated for low-frequency vibration measurement. And the dynamic performance index of the sensor has been experiment. The dynamic vibration measurements exhibit that the accelerometer provides an extremely high sensitivity of 1296pm/g, inherent frequency is 60 Hz and a considered frequency range from OHz to 25Hz. It analyzes temperature and transverse cross sensitivity of this sensor combine experiment with theory, results show that temperature and transverse sensitivity independent; 3)The stable performance is experimented under different pre-stress, the results showed that the dynamic performance is stable and its sensitivity with the change of the pre-stressed. Finally the vibration sensor in the application of optical coherence tomography system stability has carried on the preliminary discussion.