A high-resolution dynamic fiber-optic inclinometer

We proposed a high-resolution dynamic fiber-optic inclinometer based on a Fabry-Perot (F-P) interferometer and a vertical cantilever structure with an inertial mass. The F-P cavity length variation approximates the vertical cantilever deflection corresponding to the tilt angle. As a fast demodulation mechanism is applied, the F-P cavity length is absolutely and dynamically measured. The tilt angle is obtained by extracting direct current component from the real-time signals of the F-P cavity length. An experiment is carried out by using an adjustable micro-tilt platform mounted on a vibration table. The experimental results show a high tilt resolution of 0.03″ within the measurement range of ±1°. The dynamic resolution of the tilt measurement in ambient vibration is also estimated to 0.66″ with the simulated vibration frequency and amplitude of 50 Hz and 20.9 μm. Due to the dynamic measurement method, the tilt angle readouts are tolerant of ambient vibration.