Measurement of resonant mode of piezoelectric thin plate using speckle interferometry and frequency-sweeping function

This study proposes a frequency-sweeping function of electronic speckle pattern interferometry, based on standard deviation in the temporal domain. The proposed method facilities the measurement of resonant vibration, and provides stable and clear interference fringes. This study investigated the third in-plane eigenmode of a thin piezoelectric plate, using the finite element method and an impedance analyzer to verify the dynamic response obtained using the proposed method. We analyzed the vibration amplitude of interference fringes to obtain quantitative results on the sub-micron scale. The close agreement between the experimental results demonstrates the effectiveness of using the frequency-sweeping function to obtain the resonant states and provides an accurate prediction of resonance. Furthermore, statistical analysis of interference fringes obtained using the subtractive, mean, and the standard deviation method is performed. The result shows that the standard deviation method provides higher quality and stability of fringe pattern.