Topic
Acoustic interferometer
About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.
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TL;DR: In this paper, it was shown that inhomogeneous waves are even capable of predicting the experimentally observed displacement phenomena on periodic rough surfaces, and the authors have simulated these experiments using the concept of inhomogenous waves.
Abstract: Experiments are reported by Breazeale and Torbett [Appl. Phys. Lett. 29, 456 (1976)] that visualize ultrasonic backward beam displacement due to the excitation of surface waves by means of diffraction. The authors have simulated these experiments using the concept of inhomogeneous waves. Such waves have proven to be well suited in predicting beam displacements on plane interfaces. It is now found that inhomogeneous waves are even capable of predicting the experimentally observed displacement phenomena on periodic rough surfaces.
29 citations
24 Oct 1999
TL;DR: In this article, a system that uses elastic surface waves and electromagnetic waves has been developed to detect buried land mines, where an algorithm based on local spatial frequency analysis is presented to illustrate the dispersive effect of the land mine on the acoustic waves and to estimate the wave velocity as a function of position and temporal frequency.
Abstract: A system that uses elastic surface waves and electromagnetic waves has been developed to detect buried land mines. An algorithm based on local spatial frequency analysis is presented to illustrate the dispersive effect of the land mine on the acoustic waves and to estimate the wave velocity as a function of position and temporal frequency. In addition, an imaging algorithm is presented which calculates the reflected energy and generates a two-dimensional image that localizes the buried mines.
29 citations
TL;DR: An interferometer based on the differential heterodyne configuration and wavelength-scanning interferometry for measuring large step heights is presented and can accurately measure interference phases.
Abstract: An interferometer based on the differential heterodyne configuration and wavelength-scanning interferometry for measuring large step heights is presented. The proposed interferometer is less sensitive to environmental disturbances than other interferometers and can accurately measure interference phases. A tunable diode laser is utilized to illuminate the interferometer and thus solve the phase ambiguity problem. Counting the interference fringes as the wavelength is scanned through a known change in wavelength directly determines the step height. Three gauge blocks of different lengths, 5, 10, and 50 mm, are individually wrung on a steel plate to simulate large step heights. Comparing the results measured by the proposed interferometer with those by the gauge block interferometer reveals that the accuracy is approximately 100 nm.
29 citations
Patent•
20 Sep 2007
TL;DR: In this article, a method for determining characteristics of a medium in form of a liquid or a soft material was proposed, where the inner and outer surfaces of an acoustic waveguide are defined and an interior space is filled with the medium (L, L 1, L 2, L 2, LE).
Abstract: The invention relates to a method and a device for determining characteristics of a medium in form of a liquid or a soft material, the method comprising the following steps: a) providing an acoustic waveguide defining an inner surface (11, 21) and an outer surface (12, 22) and delimiting an interior space (5) to be filled with the medium (L, L1, L2, LE) to be measured such that the inner surface (11, 21) of the waveguide forms an interface with the medium, b) providing a sender (3) for feeding acoustic wave energy into the waveguide, c) providing a receiver (4) for receiving surface acoustic waves propagating along the waveguide, d) exciting surface acoustic waves in the waveguide by means of the sender (3), e) converting at least a part of the energy associated with the surface acoustic waves (S1) into volume sound waves (S3) of the medium (L, L1, L2, LE), f) propagating both surface acoustic waves (S1, S2) and volume sound waves (S3) along a direction of extension (E) of the waveguide, g) reconverting at least a part of the energy associated with the volume sound waves (S3) into acoustic wave energy of the waveguide thereby generating surface acoustic waves (S1, S2), h) determining characteristics of the medium (L, L1, L2, LE) from a signal generated by the receiver (4) upon receipt of surface acoustic waves (S2); wherein a thickness (d) of the acoustic waveguide, defined as a distance between the inner surface (11, 21) and the outer surface (12, 22) of the acoustic waveguide, is such that concurrent surface acoustic waves are propagating on both the inner and the outer surface (11, 21; 12, 22) of the acoustic waveguide.
29 citations
TL;DR: In this article, a phononic crystal flat lens was used for focusing and subwavelength imaging of surface acoustic waves (SAWs) in the time-domain by an optical technique and by numerical simulations.
Abstract: Focusing and subwavelength imaging of surface acoustic waves (SAWs) through a phononic crystal flat lens are discussed in the presented work. Experimental and numerical wave fields are obtained in the time-domain by an optical technique and by numerical simulations. Spatial distributions of the acoustic field are accessed using a temporal Fourier transform. The revealed focusing of the elastic waves in the first band of the crystal is governed by the concave equifrequency contour of the leaky-Rayleigh wave. The spatial distributions of the experimental and numerical acoustic fields also unfold subwavelength imaging of SAWs. Numerical simulations show that the imaging quality can be improved by embedding the flat lens into a medium with higher wave velocity.
29 citations