Acoustic Lens


Also found in: Medical.

acoustic lens

[ə′küs·tik ′lenz]
(materials)
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.

REFERENCES

Bergmann, L. Ul’trazvuk i ego primenenie v nauke i technike, 2nd ed. Moscow, 1957. (Translated from German.)
References in periodicals archive ?
The system incorporates an acoustic lens, rather than a phased array or electronic technique, to couple the sound fields and produce the wide dispersion.
5" midrange (called the upper woofer) covering the upper bass and lower midrange, and the acoustic lens, which loads an upper mid and tweeter in two-decker-style.
The Acoustic Lens is a complex shape consisting of ellipses in rotation, oriented so that one focal point is common to all of the ellipses in rotation while all the other focal points constitute a focal ring (a circular arc in a plane that includes all the focal points).
Two tweeters in the dashboard (left/right) with acoustic lens technology
In addition, the two dashboard speakers use Bang & Olufsen's patented acoustic lens technology for accurate sound reproduction.
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.
hiara Daraio and colleagues crafted their acoustic lens by assembling 21 parallel chains of stainless steel spheres into an array.
The acoustic lens and its sound bullets (which can exist in fluids-like air and water-as well as in solids) have "the potential to revolutionize applications from medical imaging and therapy to the nondestructive evaluation of materials and engineering systems," said Daraio.
Fourteen speakers, acoustic lens technology and a powerful digital amplifier, which produces more than 1000 watts of power, ensure a superb sound experience.
This immersion system cavity/medium is the acoustic lens that focuses the acoustic beam onto or beneath the surface of the sample.
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.
The Bang & Olufsen Advanced Sound System achieves a perfect sound quality with a total of 14 active high-end loudspeakers, B&O acoustic lens technology and more than 1000 watts of amplifier power.

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