Two-Reference Beam Double-Pulsed Holographic Interferometry with Direct Phase Measurement in Transient Processes Study

Holographic interferometry has been successfully employed to characterize both static and dynamic behavior of diverse types of structure under stress. Double-exposure pulsed holographic interferometry has been extensively used in performing the vibration analysis and qualitative investigations of deformation of the non-stationary objects. One of the most important advantages of this technique is that it can be used for quantitative measurements of the transient processes (e.g. shock wave propagation). However, in conventional double-pulsed interferometry it is sometimes difficult to get phase information from a single set of holograms.

Applying two-reference beam recording set-up to double-exposure pulsed holographic interferometry makes it possible to obtain phase-shifted interferograms from a single interferogram of the tested object and retrieve the phase information for OPD (optical path difference) map creation. Two-reference beam double-pulsed Ruby laser holographic interferometer has been adapted to transient and continuous phenomena studies. It is non-destructive, real-time, and definitive approach in identification of vibrational modes, displacements, and motion geometries.

Results of a vibration study performed by double-pulsed Ruby laser holographic interferometry for wave excited by shaker with continuous sinusoidal excitation and propagated over the car door panel surface are presented in this paper.