We present principle and application of a novel noncontact velocity measurement of surface acoustic waves (SAW) on crystals and thin films using laser interference fringes scanned at the phase velocity of SAW. The scanning interference fringes (SIF) are produced by intersecting two laser beams with a frequency difference. The SAW velocity within the laser beam spot is measured as the ratio of observed SAW frequency and predetermined wave number of the SIF. The frequency measurement can be quite precise because of a large number of generated SAW carriers and amplitude enhancement effect. The SAW velocity measurement is free from the water loading effect accompanying the leaky SAW measurements. This principle was successfully applied to evaluate Si3N4 and SiO2films deposited on Si (001) surface.
|Number of pages||6|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control|
|Publication status||Published - 1995 May|
ASJC Scopus subject areas
- Acoustics and Ultrasonics
- Electrical and Electronic Engineering