Intensity modulation-based fibre optic vibration sensor using an aperture within a proof mass

The authors propose an intensity modulation-based fibre optic vibration sensor (FOVS) using an aperture within a proof mass. It consists of an optical collimator, a mass-spring structure, a mirror, and a rectangular aperture. They verify its feasibility via experimental demonstration. For the feasibility test, they implement three lab-based prototype FOVSs with different natural frequencies and measure each FOVS's frequency response according to the base vibration and sensitivity. The experimental results for three lab-based prototype FOVSs show the sensitivities of 163, 183, and 206 mV/g, the minimum detectable accelerations of 0.082, 0.086, and 0.082 mg, and the dynamic ranges of 18-45, 26-52, and 20-120 Hz, respectively. They also experimentally demonstrate its remote sensing and multipoint sensing characteristics. The proposed FOVS has the virtues of easy controllable sensitivity and dynamic range, simple structure, and remote sensing and multipoint sensing characteristics.