Measurement Method of the Vibration Mode Shapes Using Electro-Optic Holographic Interferometry

This paper describes as Electronic Speckle Pattern Interferometry system which has been designed for measuring vibration patterns and quantitative measurement of vibration amplitude fields by using the time average method on a object. Visbility of fringe patterns is more improved by using the phase stepping and frame average method to reduce speckle and electric noise. And a bias vibration is introduced into the reference beam to shift the fringes so that fringe shift algorithms can be used to determine vibration amplitude. The experimental results are compared to those of the FFT analyzer and the FEM model analysis.