High resolution laser-interferometric probing of SAW devices

Measurements on the surface-acoustic wave profiles in various SAW devices have been performed with a scanning laser interferometer. SAW profiles at frequencies up to 1 GHz are obtained with our interferometer. Fast automatic computer control enables high-resolution scans with a large number of measuring points at speeds up to 10 000 points/hour. Our interferometer can detect below one Angstrom vibrations of the surface. These capabilities have been utilized to scan modern SAW devices. The SAW beam in a SPUDT filter has been studied. In addition, a new acoustic loss mechanism has been detected in SAW resonators operating at 1 GHz via probing an IEF filter. Our measurements serve to unfold the direct connection between the acoustic losses present at selected frequencies and the corresponding increased insertion loss of the filter at these frequencies