An optical technique for measuring vibratory motion in rotating machinery

Abstract

A method to measure the frequency and amplitude of vibration in a rotating element is presented. Using optical interferometric techniques, the flexure and torsion of a gas turbine compressor blade is shown to be measurable over the entire 360 deg of rotation. Vibrations are shown to be measurable independent of blade rotation speed; the effects of misalignment in system are shown to be small. Angular deflections from 0.5 to 500 mrad were measured in the test system.