A Method to Remotely Measure Amplitudes of Surface Vibrations with a Conventional Michelson Interferometer

摘要

This paper introduces a method to measure the amplitude of surface vibrations using a conventional Michelson interferometer. Such amplitudes may be far greater than half of the used laser's wavelength. With relatively simple signal processing it is possible to measure amplitudes at a precision that is similar to or better than the precision of the fringe counting method (FCM) and that is hardly affected by the varying tilt an oscillating surface may exhibit during the reflection of the laser beam. The proposed method allows for monitoring amplitudes which proved to be too small to be reliably measured by our version of the FCM. Using a 532 nm laser and sampling rates of 192 kHz amplitudes up to 133 μm during vibrations at 79 Hz can be measured. The sensor is easy to construct and calibrate, much cheaper than conventional multi-wavelength interferometers and does not have the need for complex signal processing.