A compact two dimensional optical fibre displacement sensor

An optical fibre two dimensional (X-Y) displacement sensor has been developed. The sensor uses a novel differential output compensation technique and is constructed with a 7-fibre sensing head and a reflecting surface with an aperture in it. The sensor successfully avoids using commonly used expensive or bulky optical components such as lenses, couplers, splitters which often introduce variations and instabilities. Therefore, the sensor is very simple, rugged and compact. Experiments showed that it is able to compensate to 99.5% of the light intensity variation when the source intensity changed by over 300%. The standard deviation of displacement measurement was less than 0.15 μm with a measuring range of 400 μm. The sensor will find use in measuring vibrations, pressure or other measurands involving small displacement