Vibration analysis by digital shearography

Digital shearography, a laser interferometric technique in conjunction with the digital image processing, has the potential for vibration analysis due to its simple optical system and sensitivity against small rigid body motions. This paper will focus on its recent developments for vibration analysis and for nondestructive testing (NDT) by dynamic (harmonic) excitation. With the introduction of real‐time observation using an automatically and permanently refreshing reference frame, both small and large rigid body motions are greatly suppressed. The development of a smaller and more mobile measuring device in conjunction with a user‐guided comfortable program shearwin enables the digital shearography to be applied easily as an industrial on‐line testing tool.