Vibration analysis in quasi-real time is studied by recording the time-averaged speckle pattern in a bismuth silicon oxide crystal (Bi12SiO20). When the crystal is illuminated with a spherical wave, the spatially structured information from the time-averaged speckle pattern leads to fringes in the Fraunhofer plane. No storage device is required when the appropriate wavelength is chosen for writing and reading out the information. Experimental results will be presented together with a comparison of measurements obtained with a Doppler shift vibrometer.
© 1981 Optical Society of America
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