Time-averaged vibration mode viewing with DSPI

摘要

We discuss an experiment for detecting small deformations by speckle interferometry. Vibration modes of an aluminium plate are observed by digital speckle pattern interferometry (DSPI). A Mach-Zender interferometer arrangement is used and the speckle interferograms are recorded with a CCD camera and processed on a computer. These fringes depend on the path differences due to the vibration of the aluminium plate from its original state. Vibration amplitudes between 0.3-0.6 μ were measured for seven vibration modes.