Fucai ZHANG^*, Jesus D. R. VALERA, Ichirou YAMAGUCHI, Masayuki YOKOTA and Godfrey MILLS

Department of Electronic Engineering, Gunma University, Tenjin-cho 1-5-1, Kiryu, Gunma 376-8515, Japan

(Received May 12, 2004; Accepted June 16, 2004)

Phase-shifting digital holography has been used for the study of vibrating objects. The time-averaged complex amplitude of Fresnel diffracted field due to a vibrating object was obtained by using a three-step phase-shifting algorithm. Taking the inverse Fresnel transform of the complex amplitude resulted in an image of the object superimposed with Bessel fringes. The Bessel fringes are contour map of the vibration amplitude. By sinusoidally modulating the phase of the reference beam at the vibration frequency, the brightest fringe could be shifted to points of interest, thus extending the measurable range of vibration amplitude.

Key words: vibration measurement, holography, phase shifting technique, digital holography

^*E-mail address: zfc@el.gunma-u.ac.jp