Plate-mode ultrasonic structure including a gel
First Claim
1. An ultrasonic structure comprising:
- a propagation medium comprising a thin planar sheet capable of supporting Lamb waves, said sheet having a thickness very much thinner than the wavelength of the Lamb waves to be propagated thereon, said propagation medium including on a surface thereof a layer of a low shear modulus material; and
electrical means coupled to the thin planar sheet of said propagation medium for producing Lamb waves in the propagation medium.
1 Assignment
0 Petitions
Accused Products
Abstract
An ultrasonic structure which has a thin planar sheet of material forming a Lamb wave propagation medium The propagation medium is coated with a gel. The structure may also include a Lamb wave generator for generating Lamb waves in the propagation medium and an output device for producing an electrical signal representative of the propagation characteristics of the Lamb waves propagating along the propagation medium. A measuring device can be included to measure selected characteristics of the output electrical signal. The propagation medium has some physical characteristics that are determined by the value of a measurand acting on the medium and the determined physical characteristics determine the propagation characteristics of the Lamb waves which are propagated along the medium. When the sensor is acted on by a measurand to determine the physical characteristics of the propagation medium, the characteristics of the electrical signal are also determined. The measuring device measures the electrical signal and provides an indication of the measurand value.
158 Citations
42 Claims
-
1. An ultrasonic structure comprising:
-
a propagation medium comprising a thin planar sheet capable of supporting Lamb waves, said sheet having a thickness very much thinner than the wavelength of the Lamb waves to be propagated thereon, said propagation medium including on a surface thereof a layer of a low shear modulus material; and electrical means coupled to the thin planar sheet of said propagation medium for producing Lamb waves in the propagation medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. An ultrasonic sensor comprising:
-
a composite structure comprising (a) a supporting frame of a first material, and (b) a propagation medium comprising a thin planar sheet of a second different material capable of supporting Lamb waves, supported peripherally by said supporting frame, said sheet having a thickness very much thinner than the wavelength of Lamb waves to be propagated thereon and having some physical characteristics determined by the value of a measurand acting thereon, said physical characteristics determining the propagation characteristics of Lamb waves to be propagated along the medium, said propagation medium including on a surface thereof a layer of a gel; electrical means coupled to the thin planar sheet of said propagation medium for producing Lamb waves in the propagation medium; output means on said sheet for producing an electrical signal representative of the determined propagation characteristics of the Lamb waves propagating along the propagation medium; and measuring means for measuring selected characteristics of said electrical signal, whereby when said sensor is acted on by a measurand, the physical characteristics of said propagation medium are determined and said electrical signal characteristics are also determined, so that said measuring means indicates the value of the measurand. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
-
-
38. The sensor as recited in claim 38, wherein the output means includes a receiving transducer, coupled to the propagation medium, for producing an electrical signal representative of the Lamb waves propagating along said propagation medium,
the electrical means includes a launching transducer, coupled to the propagation medium, for generating Lamb waves in the propagation medium, a feedback path between the receiving and launching transducers for providing feedback from the receiving transducer to the launching transducer, and a feedback amplifier in the feedback path for amplifying said electrical signal produced by the receiving transducer and fed back to the launching transducer, the sensor forming an oscillator in which Lamb waves are continuously propagated along the propagation medium, the measuring means includes frequency measuring means for measuring the oscillation frequency.
-
42. An ultrasonic structure comprising:
-
a propagation medium comprising a thin planar sheet capable of supporting Lamb waves, said sheet having a thickness very much thinner than the wavelength of the Lamb waves to be propagated thereon, said propagation medium including on a surface thereof a layer of a low shear modulus material; and optical means for the thermoelastic generation of Lamb waves in the propagation medium.
-
Specification