Applied Physics Letters · 1971 · 26 citations · 8 references
Optical MaterialsEngineeringWave OpticAcoustic MetamaterialOptical TestingLaser ApplicationsOptical MetrologyAcoustic FluxRayleigh ScatteringHigh-power LasersOptical PropertiesOptical SystemsReflectancePhotonicsPhysicsRaleigh Surface WavesClassical OpticsAcoustic PropagationBrillouin ScatteringOptical ProbingApplied PhysicsLaser Ultrasound
Data are presented on optical probing of Raleigh surface waves by Brillouin diffraction of light. The apparatus uses a low-cost 3-mW He–Ne laser and is shown to be a simple and convenient tool for acoustic losses and velocity measurements. The minimum acoustic amplitude detectable is 0.1 Å and the phase velocity is measured with an accuracy better than 0.6%. We give a simple explanation of the spatial distribution of the acoustic flux and show that in a 6-μsec quartz delay line, losses due to beam spreading are two times greater than the intrinsic loss. The results obtained with gold-coated surfaces indicate that the acoustic beam spreading is very pronounced and can partially alter some conclusions given in previous communications.
8