A non-mechanical scanning method for visualizing the mode shapes of piezoelectric devices is described. Laser speckle interference, a periodic resonator excitation, charge coupled device (CCD) image captures, and image processing using two-dimensional correlation filtering are effectively combined in this method. Even with small data averaging and a short measurement time, this method produces very clear, high-contrast mode shape images. The experimental results for several spurious modes in AT-cut quartz resonators and surface acoustic wave (S AW) devices demonstrate the applicability of the proposed method.
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