Interferometer vibration sensor with two-wavelength passive quadrature readout

A new fiber-optic extrinsic Fabry-Perot microinterferometer (cantilever beam type) vibration sensor (EFPI-V) is described. A two-wavelength demodulation scheme is implemented for eliminating signal fading effects. The theoretical model of this sensor with pronounced eigenfrequency spectrum in the acoustic range is confirmed by experimental results. Initial field tests in an experimental airport ground traffic surveillance system for vehicle detection via monitoring of structural vibrations demonstrate the application as traffic sensor.