Acoustic Lens

Also found in: Medical.

acoustic lens

[ə′küs·tik ′lenz]
Selected materials shaped to refract sound waves in accordance with the principles of geometrical optics, as is done for light. Also known as lens.

Lens, Acoustic


a device used to modify the convergence of (that is, to focus) sound beams.

Like optical lenses, acoustic lenses are bounded by two working surfaces. Acoustic lenses are made of a material for which the speed of sound differs from that in the surrounding medium, so that the refractive index n is a number other than unity. In order to attain maximum transmittance, the wave drag of the material should approximate that of the ambient and the viscous losses should be minimal.

Acoustic lenses may be solid, liquid, or gas. In a liquid or gas lens, the lens’s solid casing should exhibit maximum transmittance. For work in liquid media, the material for the lens may be plastic (n = 0.5–0.8), chloroform, or carbon tetrachloride (n = 1.3–1.4). Lenses filled with hydrogen or carbon dioxide are used along with nonhomogenous acoustic lenses filled with pellets or mesh for work in gases (for example, air). Nonhomogeneous diverging air lenses are used to improve the directivity characteristics of loudspeakers. Solid and liquid lenses are used for acoustic images, flaw detection, medical diagnosis, and the concentration of ultrasound for a variety of technological and biological purposes.


Bergmann, L. Ul’trazvuk i ego primenenie v nauke i technike, 2nd ed. Moscow, 1957. (Translated from German.)
References in periodicals archive ?
The tweeters are mated to a new, patented fourth-generation Acoustic Lens Waveguide that optimizes the blend between the tweeter and woofers and improves off-axis performance for smoother, more consistent performance over a wide listening area.
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It is this structure that forms a visible bulge on the animal's head and researchers say it acts as an adjustable acoustic lens, focusing the sound into a beam and altering the size of that beam.
Figure 4 demonstrates a similar model of the distortion of the ultrasound image, when the specimen has defects filled with liquid, for example, water spots, performing a sort of acoustic lens function and causing unwanted ultrasound beam breakage, as in the example.
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hiara Daraio and colleagues crafted their acoustic lens by assembling 21 parallel chains of stainless steel spheres into an array.
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Among his achievements, Praestgaard helped implement the acoustic lens technology, acquired from Sausalito Audio Works, in the award winning Beolab 5 loudspeaker, which also used Adaptive Bass Control technology developed in Praestgaard's department at the University.

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