Real-time stroboscopic holographic interferometry using sillenite crystals for the quantitative analysis of vibrations

A breadboard holographic interferometer that uses a photorefractive sillenite crystal under anisotropic diffraction configuration is presented for application of quantitative vibration measurements. After the hologram of the object at rest is recorded, a stroboscope is used to observe the stable pattern of the vibrating object and phase-shifting is introduced for quantitative measurements. It is shown that this system can measure modal displacements of objects of typically 23 X 23 cm(2) with high accuracy (lambda/40) by using a continuous YAG laser emitting 490 mW at 532 nm. The error sources are investigated and particularly a systematic error arising from the stroboscopic process can be calculated and eliminated. (C) 1998 Elsevier Science B.V.