Acoustic interferometer

About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.

Reflection of plane elastic waves in tetragonal crystals with strong anisotropy.

Abstract: Propagation and reflection of plane elastic waves in the acousto-optic crystals tellurium dioxide, rutile, barium titanate, and mercury halides are examined in the paper The reflection from a free and flat boundary separating the crystals and the vacuum is investigated in the (001) planes in the case of glancing acoustic incidence on the boundary The analysis shows that two bulk elastic waves may be reflected from the crystal surface The energy flow of one of the reflected waves in paratellurite and in the mercury compounds propagates in a quasi-back-direction with respect to the incident energy flow It is proved that energy flows of the incident and reflected elastic waves are separated by a narrow angle of only a few degrees It is also found that the relative intensity of the unusually reflected waves is close to a unit in a wide variety of crystal cuts General conclusions related to acoustic propagation and reflection in crystals have been made based on the examined phenomena in the materials

Surface acoustic wave device for sensing the presence of chemical agents

Abstract: A surface acoustic wave device is provided for sensing the presence of chemical agents by chemo-electronic means. The device includes a quartz substrate and means deposited on the substrate for propagating and receiving surface acoustic waves along the surface of the substrate. Regions are provided on the substrate containing etched tunnels, the walls of the etched tunnel being coated within with a chemical substance sensitive to the chemical agent to be detected. When surface acoustic waves are caused to pass over these regions, the reaction of the chemical agent to be detected with the chemical substance causes a change in the acoustic wave velocity.

Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies

Abstract: We investigate the viscoelastic properties of confined molecular nano-layers by time resolved optical pump-probe measurements. Access to the elastic properties is provided by the damping time of acoustic eigenmodes of thin metal films deposited on the molecular nano-layers which show a strong dependence on the molecular layer thickness and on the acoustic eigen-mode frequencies. An analytical model including the viscoelastic properties of the molecular layer allows us to obtain the longitudinal sound velocity as well as the acoustic absorption coefficient of the layer. Our experiments and theoretical analysis indicate for the first time that the molecular nano-layers are much more viscous than elastic in the investigated frequency range from 50 to 120 GHz and thus show pronounced acoustic absorption. The longitudinal acoustic wavenumber has nearly equal real and imaginary parts, both increasing proportional to the square root of the frequency. Thus, both acoustic velocity and acoustic absorption are proportional to the square root of frequency and the propagation of compressional/dilatational acoustic waves in the investigated nano-layers is of the diffusional type, similar to the propagation of shear waves in viscous liquids and thermal waves in solids.