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 μm core fiber, one acting as the source and the other one as receiving fiber. Displacement resolution of the order of 2.5 μm has been measured with a sensitivity of about 1.6 mV/μm for a dynamic range of 700 μm. The measured output is checked against the expected theoretical one and also other experimental results and good agreement are obtained.