Kalibrierungsfreie Messung von Amplitude und Phase hochfrequenter Schwingungen Calibration-Free Measurement of Amplitude and Phase of High-Frequency Vibrations

We describe a novel approach to the interferometric observation of surface acoustic waves. The technique allows the extraction of the absolute amplitude and phase of high-frequency vibrations independent of surface reflectivity, laser power variation, or the sensitivity of the interferometer. This is possible through synchronized acquisition of the interferometer output with a vector network analyzer and a digital sampling ocscilloscope. The subsequent digital signal processing extracts the information wanted from the measured values. To verify the method, we calculated the excitation of acoustic waves by the delta function model and compared the results with the measurement. Eventually we constructed the anisotropic slowness curve of the piezoelectric substrate, which is of value for the characterization of thin-film material properties.