Cost-effective vibration and displacement measurement using range-resolved interferometry

A recently developed range-resolved optical interferometric signal processing technique is applied to vibration and displacement sensing with fibre-based beam delivery. The technique is demonstrated to allow the simultaneous acquisition of high-quality, high resolution relative displacement measurements (ߪ ൌ ͵ ) based on interferometric phase evaluation along with coarser ሺߪ ൌ ͲǤͲͷ ) absolute displacement measurements. The interferometric relative displacement data can be used for vibrometry measurement and to yield high-quality derivative velocity and acceleration data suitable for position control applications. The absolute data can serve as an additional proximity sensor. The sensing approach employs cost-effective diode lasers, off-the-shelf digital processing hardware and a very simple optical setup, and can, due to the use of a collimated beam, operate over a wide range of working distances.