Method and system for coupling acoustic energy using shear waves
First Claim
1. An acoustic system, comprising:
- an acoustic waveguide having a waveguide axis along which acoustic waves are capable of being longitudinally transmitted, and a waveguide periphery; and
an acoustic shear wave transducer positioned to occupy at least two different positions at the periphery, the shear wave transducer adapted to transduce shear waves propagating in a plane substantially perpendicular to the waveguide axis;
wherein the at least two different positions are selected such that, when the transducer is driven, the transducer generates shear waves which propagate toward the waveguide axis and converge in mutual reinforcement, to thereby form a sweet spot within the acoustic waveguide, and the waveguide is effective to propagate corresponding longitudinal waves along the waveguide axis.
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Accused Products
Abstract
A system and method for coupling acoustic energy within a waveguide provides highly efficient and sensitive acoustic energy generation and detection. In particular, an ultrasound angioplasty system is described which makes use of an end-fire array of ring transducers to produce highly directionalized sound within an acoustic waveguide. The transducers can be made circularly symmetric, and may be composed of multiple segments for generating sound waves in independent x and y spatial modes within the acoustic waveguide. Each ring transducer is optimally spaced 1/2λL from its neighbor transducers, such that alternate transducers transduce 180-degrees out of phase, and may have their electrical end inverted for common drive, or for summing of transducer electrical outputs when the array is used as a detector. The phased array may also be used in a resonant acoustic energy system used to detect pressure variations or reflections from a substance, for example, for detecting the progress of chemical reactions, liquid level sensing, etc., imaging, or in various other ultrasound applications.
47 Citations
19 Claims
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1. An acoustic system, comprising:
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an acoustic waveguide having a waveguide axis along which acoustic waves are capable of being longitudinally transmitted, and a waveguide periphery; and an acoustic shear wave transducer positioned to occupy at least two different positions at the periphery, the shear wave transducer adapted to transduce shear waves propagating in a plane substantially perpendicular to the waveguide axis; wherein the at least two different positions are selected such that, when the transducer is driven, the transducer generates shear waves which propagate toward the waveguide axis and converge in mutual reinforcement, to thereby form a sweet spot within the acoustic waveguide, and the waveguide is effective to propagate corresponding longitudinal waves along the waveguide axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In an acoustic delivery system that includes an excitation source, an acoustic generator that the excitation source causes to generate acoustic energy, and a waveguide that delivers acoustic waves from the generator to a remote location along a waveguide transmission axis, the improvement comprising:
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at least two shear wave transducers of the generator, positioned at different points along the waveguide axis, each transducer having a shear wave transmission plane which is perpendicular to the waveguide transmission axis, each transducer configured to generate shear waves of a predetermined frequency; wherein the different points of the shear wave transducers are selected to cause constructive reinforcement of the acoustic waves when the transducers are driven at the predetermined frequency. - View Dependent Claims (11, 12, 13, 14)
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15. A method of transducing acoustic energy using a waveguide having a waveguide axis along which acoustic waves are longitudinally transmitted, a plurality of shear wave transducers having an associated acoustic frequency, and electrical couplings of the transducers, which carry electric signals corresponding to the particular acoustic frequency, comprising:
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positioning the shear wave transducers proximate to the waveguide and along it such that the transducers transduce shear waves which propagate along a shear wave plane perpendicular to the waveguide axis; spacing the plurality of transducers along the waveguide axis at fractions of a wavelength (corresponding to the particular acoustic frequency); and equalizing relative phases of the plurality of transducers by providing phase lags to them; wherein the shear wave transducers are spaced at intervals relative to the phase lags such that the shear wave transducers collectively form a phased array tuned to the particular acoustic frequency, to thereby transduce the acoustic energy. - View Dependent Claims (16, 17, 18, 19)
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Specification