Pulsed digital holographic interferometry for dynamic measurement of rotating objects with an optical derotator

A method for measuring dynamic deformations of rotating objects with pulsed digital holography is described. An optical derotator is used to compensat e for the rotation. A CCD camera is used to record two holograms with a sho rt time separation (20 mus). Results of deformations between the recordings are obtained after subtraction of the phase distribution between the two d igital holograms. Fringe phase maps of the phase subtraction of two hologra ms compensated by the derotator and recorded with a Q-switched double-pulse d ruby laser are presented. A flat disk and the blades of a fan were invest igated. We used an optical arrangement that allowed us to improve laser ill umination and energy efficiency. Experimental results on quantitative evalu ation of dynamical out-of-plane deformations are presented. (C) 2001 Optica l Society of America.