VISUALIZATION OF 50 MHZ SURFACE-ACOUSTIC-WAVE PROPAGATION USING STROBOSCOPIC PHASE-SHIFT INTERFEROMETRY

A stroboscopic phase-shift interferometry has been developed to visual ize surface acoustic wave (SAW) propagation on SAW devices quantitativ ely. The developed interferometry is a Fizeau-type one with a multi-mo de semiconductor laser diode and an optical isolator. With the laser l ight illuminating stroboscopically, observed interference intensity gi ves information about average displacements of the vibrations. Fifty M Hz SAW propagation on the surface of the SAW device has been measured with the interferometry. Distribution of the SAW along the propagation path has been observed, whose amplitude is 3 nm (p-p). Repetition acc uracy evaluated with the root mean square method is 1/2500 of the lase r wavelength. The system is useful for estimating and improving perfor mances of micro-devices.