Automatic Scanning Process
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The measurement of the displacement in the z direction can be accomplished by using a laser triangulation sensor scanning 2 dimensions (radius r and angle φ) of the target surface.
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The transducer under test is rotated by a turn table (φ coordinate) and shifted by a linear actuator (r coordinate). An additional actuator is required to adjust the laser to the optimal distance in the z dimension.
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At each measurement point the transducer is excited by a shaped stimulus sweep giving sufficient spectral resolution and high SNR in the measured response over the whole audio band (< 25 kHz). |