Acoustic interferometer

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

Acoustic anisotropy of piezoelectric PbB4O7 crystals studied by laser ultrasonics

Abstract: Acoustic anisotropic properties of PbB4O7 crystals are investigated and discussed. The slowness curves of three bulk waves as well as the surface waves for the plates with different cut directions are calculated by considering piezoelectric effects. The theoretical calculations are in agreement with experimental results determined by laser ultrasonic technique. On the other hand, the excitation efficiency of surface waves of PbB4O7 crystals is obtained by calculating the change of the velocities of acoustic surface waves get from the plates bare and deposited by a thin metal film. The results of this paper can be used for selecting PbB4O7 crystal orientations for designing the related devices.

Simultaneous realization of negative group velocity, fast and slow acoustic waves in a metamaterial

Abstract: An acoustic metamaterial is designed based on a simple and compact structure of one string of side pipes arranged along a waveguide, in which diverse group velocities are achieved. Owing to Fabry-Perot resonance of the side pipes, a negative phase time is achieved, and thus, acoustic waves transmitting with negative group velocities are produced near the resonant frequency. In addition, both fast and slow acoustic waves are also observed in the vicinity of the resonance frequency. The extraordinary group velocities can be explained based on spectral rephasing induced by anomalous dispersion on the analogy of Lorentz dispersion in electromagnetic waves.

A Fixed Path Acoustic Interferometer for the Study of Matter

Abstract: The resources of ultrasonic interferometry have been extended by the development of an interferometer of fixed path. In this device a fixed distance is maintained between a piezoelectric resonator and a reflector. Variation of acoustic reaction of the medium between them is secured by a variation of the acoustic wave‐length produced by changes of temperature, pressure or composition, or in liquids and solids by a change in frequency. It is particularly adaptable to the study of the velocity of sound in gases from the lowest temperatures attainable to approximately 500°C and over a pressure range of at least 100 atmospheres because of the elimination of moving parts and packed joints. The method is also applicable, when results are obtained with two precisely known lengths of path, to the measurement of acoustic absorption and reflection coefficients. Results obtained with air and CO2 are given.

Wideband guided - Wave acoustooptic Bragg devices using multiple tilting surface acoustic waves

Abstract: waveslinch gives 90% of the response of an ideally flat mirror. To isolate the laser from the interferometer, and to provide means for varying the beam balance in the two legs, a polarizing beam splitter (PBS) with a quarter wave plate in each leg of the interferometer is used. The polarization angle of the incident beam is varied to change the beam balance. A second PBS is used to analyze the interference. By using both outputs from this second PBS, which has a 180” relative phase shift, the response is doubled and common mode noise is minimized. This system, with associated electronics and display circuitry, has been used to measure and display ultrasonic waves, and some examples are given. It is being used to measure ultrasonic transducer response, to measure and display the interaction between biologic tissue and ultrasound, and as an aid in the design of ultrasonic lenses. In this paper we want to stress the optical design of the system and discuss other applications in the measurement of small motions of mechanical objects.