Acoustic interferometer

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

A New Ultrasonic Interferometer for Liquids

Abstract: An interferometer has been developed which makes use of the free surface of a liquid as a reflector. The emitter is an optically plane quartz crystal which is held perfectly horizontal at the bottom of a vertical liquid column. Changes in the column height produce the effects which are used to measure absorption in the liquid. A sensitive method of adding liquid makes the instrument usable at frequencies well above six megacycles. The leveling is sensitive and positive.

Measurement of material anisotropy by dual-probe laser interferometer

Abstract: A novel dual-probe laser interferometer, which has the advantage that it measures the surface displacements of the same surface wave at two locations, has been used to measure the speeds of surface waves and pseudo-surface waves on a silicon single crystal. Two configurations have been investigated. When the distance between the two points of detection is large relative to the length of the acoustic wave, the two signals detected by the probes are separated in the time domain. Hence the signal travel time can be found by the autocorrelation method. When the distance between the two points of detection is short relative to the acoustic wave, a composite signal is obtained consisting of two overlapping signals. Then the power cepstrum method is employed to extract the signal travel time between the probe points. The speeds for both types of surface waves are shown as functions of direction relative to the [001] crystal axis. The results have been compared with theoretical calculations and line-focus acoustic microscopy measurements.

Acoustic imaging and mirage effects with high transmittance in a periodically perforated metal slab

Abstract: In this paper, we present a high-quality superlens to focus acoustic waves using a periodically perforated metallic structure which is made of zinc and immersed in water. By changing a geometrical parameter gradually, a kind of gradient-index phononic crystal lens is designed to attain the mirage effects. The acoustic waves can propagate along an arc-shaped trajectory which is precisely controlled by the angle and frequency of the incident waves. The negative refraction imaging effect depends delicately on the transmittance of the solid structure. The acoustic impedance matching between the solid and the liquid proposed in this article, which is determined by the effective density and group velocity of the unit-cell, is significant for overcoming the inefficiency problem of acoustic devices. This study focuses on how to obtain the high transmittance imaging and mirage effects based on the adequate material selection and geometrical design.