Fiber optic displacement sensor using a coated lens optic

Design and operation of an optomechanical displacement sensor employing a reflecting coated lens is reported. The light intensity modulation is based on the relative motion of the optical fibers and the lens. The modulated intensity has been measured by using a pair of 450 mum core fiber, one acting as the source and the other one as receiving fiber. Displacement resolution of the order of 2.5 mum has been measured with a sensitivity of about 1.6 mV/mum for a dynamic range of 700 mum. The measured output is checked against the expected theoretical one and also other experimental results and good agreement are obtained. (C) 2000 American Institute of Physics. [S0034-6748(00)03410-9].