An optical sensor for the dynamic measurement of proximity is presented. The sensor combines an extrinsic geometric transducer with interferometric encoding for high vibration sensitivity. Static calibration showed a unique variation in interference contrast over at least 60 fringes, leading to a measurement range of 20 μm and a resolution of at least 0.033μm. Dynamic excitation by using low-amplitude vibrations at 3.6 kHz showed a similar contrast variation, verifying fringe discrimination up to the sixth order. With verification of dynamic performance over all 60 fringes, the sensor should offer a low-cost approach to vibration monitoring in electrical switchgear.
© 1997 Optical Society of America
Tarun Kumar Gangopadhyay, Philip James Henderson, and Anthony David Stokes, "Vibration monitoring by using a dynamic proximity sensor with interferometric encoding," Appl. Opt. 36, 5557-5561 (1997)