In-plane mode shape visualization of piezoelectric resonators using stroboscopic laser irradiation

A full-field imaging method has been presented that rapidly measures the in-plane mode shapes of piezoelectric devices with a laser system synchronized to the resonator driving signal. By using two images of the maximum difference in interference conditions, measurement sensitivity was improved to 15 dB as converted to the resonator drive level. The measurement results for a 100 MHz fundamental resonator were not completely clear, but the vibrational area was-clearly identified with the proposed method. We also estimated the absolute vibrational amplitude of high-frequency resonators with the proposed system, based on the laser speckle method.