A 2-DIMENSIONAL FIBEROPTIC VIBRATION SENSOR

A new type of two-dimensional fibre-optical vibration sensor is presented. The deflection of a uniform elastic cantilever is sensed by an optical lever and a dual-axis linear position photosensor. The vibrometer is designed to measure vibrational amplitudes and frequencies simultaneously in two perpendicular directions with a linearity error less than 0.1%. An amplitude of 400 mu m, resolution within 0.5 mu m, dynamic range of three decades (64 dB) and a cross talk of -42 dB between the channels are measured. The recorded two-dimensional vibrational spectrum of a motor-driven unit shows different frequency components in horizontal and vertical directions. The high-power photodiode, high-responsivity photosensor and a compact shielded construction make the proposed sensor stable in the environment of high-power machines and strong electromagnetic interference. By varying the sensor's parameters, the proposed sensor can be designed to have almost any desired response and sensitivity. It can also be used as a seismograph.