A digital holographic method for the measurement of piezoelectric transformer vibrations

Method for the measurements of the out-of-plane displacement on the surface of vibrating object is presented. The method is based on the frequency-shifted time average digital holographic interferometry employing the principle of phase shifting. This approach allows for a significant noise reduction, which results in the high sensitivity of measurements. The method makes it possible to measure the vibrations with amplitudes in the nanometer range over the whole measured surface. The method was applied to the visualization of the out-of-plane vibration modes of piezoelectric transformers. The amplitude and modal shapes were measured with a very high resolution. Results of measurement were used to judge the influence of mounting on the electrical properties of piezoelectric transformers in operation.