United States Patents
- 6,963,399
Title: Method and Apparatus for Quantifying an "Integrated Index" of a Material Medium
Inventors: R. Cargill, C. Zanelli
Assignee: R. Cargill, C. Zanelli
Date: 11/08/2005
[PDF 1.7Mb]
Abstract>US Patent: 6,963,399
Title: Method and Apparatus for Quantifying an "Integrated Index" of a Material Medium
Inventors: Robert L. Cargill, Claudio I. Zanelli
Assigned: R. Cargill, C. Zanelli
Date: 11/08/2005An apparatus for and method of calculating an integrated index of a transparent, translucent or opaque material for a desired wavelength range, the method comprising measuring a filtered value of the material as a function of wavelength within the desired wavelength range and calculating a protection index from the measured filtered value. The integrated index is used to quantify the ultraviolet, infra-red, erythermal or aphakic exposure properties of the material. In addition, the integrated index is used to quantify the photopic and/or scotopic response capabilities of the material. Further, the integrated index is used to quantify the differential or mean color indices of the material in comparison to the color spectrum or another material. Moreover, the integrated index is used to quantify the heat flux absorbed by the material.
- 6,863,653
Title: Ultrasound Device for Axial Ranging
Inventors: C. Zanelli, M. Rosinko, G. Stone, S. Daniel
Assignee: Eclipse Surgical Technologies, Inc.
Date: 03/08/2005
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Abstract>US Patent: 6,863,653
Title: Ultrasound Device for Axial Ranging
Inventors: Claudio I. Zanelli, Michael J. Rosinko, Gregg W. Stone and Steven A. Daniel
Assigned: Eclipse Surgical Technologies, Inc.
Date: 07/23/1991An apparatus for treatment of body tissue includes a treatment apparatus configured to be inserted into a patient. The treatment apparatus has a distal portion, a distal end, a proximal portion and an axis. An ultrasound transducer is positioned at the distal portion of the treatment apparatus. The ultrasound transducer includes a distal ultrasound energy delivery surface and a proximal ultrasound energy delivery surface. An ultrasound energy attenuator member is positioned adjacent to the proximal ultrasound energy delivery surface and is made of a material to at least partially attenuate ultrasound energy from the proximal ultrasound energy delivery surface.
- 6,546,276
Title: Ultrasonic Based Detection of Interventional Device Contact and Alignment
Inventors: C. Zanelli
Assignee: none
Date: 04/08/2003
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Abstract>US Patent: 6,546,276
Title: Ultrasonic Based Detection of Interventional Medical Device Contact and Alignment
Inventors: Claudio I. Zanelli
Assigned: none
Date: 04/08/2003A method and apparatus for remotely monitoring the location of an interventional medical device (IMD) using ultrasonic signals. Both the proximity and alignment of the IMD are calculated from ultrasound signals reflected off the tissue surface. The inclusion of an offset between the distal end of the IMD and the ultrasound transducer enables accurate position and alignment monitoring of when then IMD is in contact with, or ver close to, the tissue surface. The timing of the reflected signal is used to measure the alignment of the IMD in 3D space or perpendicularity to a given surface. The present invention may be used as a location indicator within a wide variety of IMDs and in a wide variety of medical procedures.
- 6,515,657
Title: Ultrasonic Imager
Inventors: C. Zanelli
Assignee: none
Date: 02/04/2003
[PDF]
Abstract>US Patent: 6,515,657
Title: Ultrasonic Imager
Inventors: Claudio I. Zanelli
Assignee: none
Date: 02/04/2003An ultrasound imaging system superimposes sectional views created from volumetric ultrasound data and the location data for an interventional device, such as a catheter. The position of an interventional medical device may be shown, in one or more views, relative to organs and tissues within a body as the interventional device is moved. The interventional device positional data is updated continuously and is superimposed on tissue images that may be updated less frequently, resulting in real-time or near teal-time images of the interventional device relative to the tissues.
The superimposed images permits medical personnel to perform procedures such as angiograms with minimal or no exposure of patients to x-rays and contrasting dye. The look and feel of the familiar fluoroscopy-like imaging may be maintained, or a three dimensional real-time, or near real-time projected image of the interventional medical device relative to an organ or tissue may be provided.
- 6,514,220
Title: Non Focused Method of Exciting and Controlling Acoustic Fields in Animal Body Parts
Inventors: H. Melton, Jr., J. Fearnside and C. Zanelli
Assignee: Walnut Technologies
Date: 02/04/2003
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Abstract>US Patent: 6,514,220
Title: Non Focused Method of Exciting and Controlling Acoustic Fields on Animal Body Parts
Inventors: Hewlett E. Melton, Jr., James T. Fearnside, and Claudio I. Zanelli
Assignee: Walnut Technologies
Date: 02/04/2003The effect of ultrasonic irradiation of a human or other animal body portion is enhanced by operating the body portion as a trapped mode resonator. The intensity and location of resonances within the body portion is controlled by controlling such variables as the amplitude, frequency and / or phase of the ultrasound irradiation. This minimizes the overall energy required to be applied to the body portion in order to achieve a desired localized intensity field.
- 6,436,059
Title: Detection of IMD Contact and Alignment Based on Changes in Frequency Response Characteristics
Inventors: C. Zanelli
Assignee: none
Date: 08/20/2002
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Abstract>US Patent: 6,436,059
Title: Detection of IMD Contact and Alignment Based on Changes on Frequency Response Characteristics
Inventors: Claudio I. Zanelli
Assigned: none
Date: 08/20/2002A method and apparatus for remotely monitoring the location of an interventional medical device (IMD) which monitors changes in frequency response characteristics of a sensor. Embodiments of the present invention may use changes in the complex impedance properties of the sensor, at antiresonance, or changes on the resonant frequency of an LC circuit to indicate whether or not the IMD is in contact with a tissue surface. The present invention is adapted for use in conjunction with a wide variety of IMDs, and in a wide variety of medical procedures.
- 6,093,883
Title: Ultrasound Intensity Determining Method and Apparatus
Inventors: N. Sanghvi, F. Fry, C. Hennige and C. Zanelli
Assignee: Focus Surgery, Inc.
Date: 07/25/2000
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Abstract>US Patent: 6,093,883
Title: Ultrasound Intensity Determining Method and Apparatus
Inventors: Narendra T. Sanghvi, Francis J. Fry, Carl W. Hennige and Claudio I. Zanelli
Assignee: Focus Surgery, Inc.
Date: 07/25/2000A method of treatment by ultrasound comprises providing a first, ultrasound field intensity-to-voltage transducer sized for insertion into the vicinity of a treatment site and a second ultrasound treatment transducer. The free field intensities created by the second transducer in response to various second transducer exciting signal levels are determined. The first transducer outputs in the the free field in response to various second transducer exciting signal levels are also determined. The first transducer is inserted into the vicinity of the treatment site, and the second transducer is positioned to create an ultrasound field at the treatment site. The distance from the second transducer to the first transducer is determined. An exciting signal is applied to the second transducer. The output from the first transducer is determined. The level of the exciting signal applied to the second transducer, the determined distand and the first transducer output are employed to determine the attenuation coefficient of the tissues between the second transducer and the first transducer.
- 6,024,703
Title: Ultrasound Device for Axial Ranging
Inventors: C. Zanelli, J. Giba, M. Davis and D. Murphy-Chutorian
Assignee: Eclipse Surgical Technologies, Inc.
Date: 02/15/2000
[PDF 1.2MB]
Abstract>US Patent: 6,024,703
Title: Ultrasound Device for Axial Ranging
Inventors: Claudio I. Zanelli, Jeffrey J. Giba, Micharl A. Davis, and Douglas Murphy-Chutorian
Assignee: Eclipse Surgical Technologies, Inc.
Date: 02/15/2000A treatment tool such as a catheter, MIS or other surgical tool apparatus for placement within a heart chamber, organ aperture or other body opening and axial ranging therein, the apparatus particularly adapted for laser-assisted percutaneous transmyocardial revascularization (MTR). At the distal end of the tool is an annular ultrasound transducer with associated structure, positioned to transmit ultrasound signals substantially axially aligned with the axis of the treatment tool to the cardiovascular tissue, the transducer further receiving returning signals from the cardiovascular tissue to be treated. In a preferred embodiment, the transducer comprises a piezoelectric crystal material. The transducer assembly is attached to the distal tip of the tool such that a laser delivery means or other functional device can be extended through the lumen of the tool and the annular ultrasound transducer. In a preferred embodiment, the invention is a modular ultrasound device capable of being detachable attached to a steerable catheter, MIS or other surgical tool apparatus. The system also comprises a signal interface extending from the ultrasound transducer and signal processing component operatively connected to the signal interface for real time determination of at least one boundary surface of cardiovascular tissue relative to one or more positions of the distal tip of the treatment tool. A method of delivering laser energy to tissue is disclosed, the methods delivery means adjacent toe front surface of the tissue, delivering laser energy to the tissue, receiving ultrasound signals reflected from at least the rear surface of the tissue, and determining the distance between the firing tip of the laser delivery means and the rear surface of the tissue. In a preferred embodiment, the method includes quantitative determination of the contracility or motion of the beating heart, such that changes in the depth of tissue can be used to control the channel depth or other treatment parameters. Retrolasing can also be achieved by mechanically piercing the tissue to a determined depth based on axial ranging measurements, and retracting the treatment tool while simultaneously delivering laser energy therefrom.
- 5,873,902
Title: Ultrasound Intensity Determining Method and Apparatus
Inventors: N. Sanghvi, F. Fry, C. Hennige and C. Zanelli
Assignee: Focus Surgery, Inc.
Date: 02/23/1999
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Abstract>US Patent: 5,873,902
Title: Ultrasound Intensity Determining Method and Apparatus
Inventors: Narendra T. Sanghvi, Frances J. Fry, Carl W. Hennige, and Claudio I. Zanelli
Assignee: Focus Surgery, Inc.
Date: 02/23/1999A method of treatment by ultrasound comprises providing a first, ultrasound field intensity-to-voltage transducer sized for insertion into the vicinity of a treatment site and a second ultrasound treatment transducer. The free field intensities created by the second transducer in response to various second transducer exciting signal levels are determined. The first transducer outputs in the free field in response to various second transducer exciting levels are also determined. The first transducer is inserted into the vicinity of the treatment site and the second transducer is positioned to create an ultrasound field at the treatment site. The distance from the second transducer to the first transducer is determined. An exciting signal is applied to the second transducer. The output of the first transducer is determined. The level of the exciting signal applied to the second transducer, the determined distance and the first transducer output are employed to determine the attenuation coefficient of the tissues between the second transducer and the first transducer.
- 5,706,820
Title: Ultrasonic Transducer with Reduced Elevation Sidelobes and Method for the Manufacture Thereof
Inventors: J. Hossack and S. Howard
Assignee: Acuson Corporation
Date: 01/13/1998
Abstract>US Patent: 5,706,820
Title: Ultrasonic Transducer with Reduced Elevation Sidelobes and Method for the Manufacture Thereof
Inventors: John A. Hossack and Samuel M. Howard
Assigned: Acuson Corporation
Date: 01/13/1998An ultrasound transducer and the method for the manufacture thereof which is designed to reduce the generation of elevational sidelobes. At least kerf is formed in each end region of a body of piezoelectric material. The kerfs define therebetween a center region formed solely of piezoelectric material. The kerfs are filled with a second material.
- 5,657,295
Title: Ultrasonic Transducer with Adjustable Elevational Aperture and Methods for Using Same
Inventors: S Howard
Assignee: Acuson Corporation
Date: 08/12/1997
Abstract>US Patent: 5,657,295
Title: Ultrasonic Transducer with Adjustable Elevational Aperture and Methods for Using Same
Inventors: Samuel M. Howard
Assigned: Acuson Corporation
Date: 08/12/1997An ultrasound transducer includes transducer segments having a non-uniform thickness layer of relaxor ferroelectric material and coupled to a source of biasing voltage thereto. The elevational aperture is controlled by varying biasing voltage applied to the layer of relaxor ferroelectric material.
- 5,520,188
Title: Annular Array Transducer
Inventors: C. Hennige, S. DeMarta and C. Zanelli
Assignee: Focus Surgery Inc.
Date: 05/28/1996
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Abstract>US Patent: 5,520,188
Title: Annular Array Transducer
Inventors: Carl W. Hennige, Stan DeMarta and Claudio I. Zanelli
Assignee: Focus Surgery Inc.
Date: 05/28/1996A transducer for use in a localization and therapeutic ultrasound system. The transducer of the present invention includes multiple elements that are driven separately. The elements operate together to focus a continuous wave ultrasound beam at a focal zone that is at a variable distance from the elements. The transducer includes a mechanism to adjust the focal distance so that the focal zone may be moved to multiple depths.
- 5,515,169
Title: Spectral Wavelength Discrimination System and Method for Using
Inventors: R. Cargill, E. Gombocz, C. Zanelli and B. Swaby
Assignee: Lab intelligence Inc and Optical Coating Laboratory, Inc.
Date: 05/07/1996
[PDF 1.3MB]
Abstract>US Patent: 5,515,169
Title: Spectral Wavelength Discrimination System and Method for Using
Inventors: Robert L. Cargill, Erich Gombocz, Claudio I. Zanelli, and Basil Swaby
Assignee: Labintelligence Inc and Optical Coating Laboratory, Inc.
Date: 05/07/1996A spectral wavelength discrimination system and method for using are provided which allows the wavelength of a beam of radiation to be accurately determined using compact inexpensive optics and electronics. The system is particularly useful for identifying the emission wavelength of a multi-component marker system which includes a plurality of components having different wavelength ranges. The system comprises a wavelength selective beamsplitter, termed a Linear Wavelength Filter, that directs predetermined fractions of the beam at each wavelength into each of two output beams. The intensities of these output beams are measured. The measurements and selected system parameters, including the beamsplitter spectral characteristics and the detector sensitivity characteristics are used in a special algorithm for performing Fourier based analysis is the wavelength of the bean radiation. The system employs various optical components and structures to achieve the desired spatial resolution and sensitivity. Multiple channel devices and other special configurations are also described.
- 5,463,593
Title: Apparatus for Quantitative Measurement of Ultrasonic Wave Power Distribution
Inventors: C. Zanelli and F. Whitehead
Assignee: Claudio I. Zanelli, Intec Research Company
Date: 10/31/1995
[PDF 1.2MB]
Abstract>US Patent: 5,463,593
Title: Apparatus for Quantitative Measurements of Ultrasonic Wave Power Distribution
Inventors: Claudio I. Zanelli and Frank R. Whitehead
Assignee: Claudio I. Zanelli, Intec Research Company
Date: 10/31/1995A schlieren imaging system provides quantitative imagins suitable for testing medical equipment. One embodiment includes precision optics which form an image of a volume of medium through which an ultrasonic acoustic wave propagates. A spatial filter passes diffracted light but blocks other light. A camera forms an image of the medium from the diffracted light so that regions of the medium which deffract light have higher light intensity along an optical path through the volume. Integrated pressure is determined from a look-up table which relates oredicted light intensity to pressure values which cause the predicted light intensity. The system is calibrated by forming an image of a reference ultrasonic acoustic wave and determining a relationship between the image intensities and predicted intensities. The system may include a timing circuit which periodically activates and deactivates a transducer and causes emission of synchronized pulses of light. The pulses of light are synchronized with a selected delay after activations of the transducer, so that an image is formed which shows an ultrasonic acoustic wave that has evolved during the delay.
- 5,297,553
Title: Ultrasound Transducer with Improved Rigid Backing
Inventors: J. Silwa, Jr., S. Ayter, C. Sridhar, J. Mohr III, S. Howard and M. Ikeda
Assignee: Acuson Corporation
Date: 03/29/1994
Abstract>US Patent: 5,297,553
Title: Ultrasound Transducer with Improved Rigid Backing
Inventors: John W. Sliwa, Jr., Sevig Ayter, Champa G. Sridhar John P. Mohr III, Samuel M. Howard and Michael H. Ikeda
Assigned: Acuson Corporation
Date: 03/29/1994An ultrasound transducer comprising an array of individual piezoelectric transducer elements mounted upon an improved backing comprising rigid polymeric or polymer-coat particles fused into a macroscopically rigid structure having remnant tortuous permeability to provide high acoustic attenuation and to permit fluid passage into the backing structure during fabrication.
- 5,155,708
Title: Acoustic Wave Sensor and Method of Making Same
Inventors: R. Bedi and A. Selfridge
Assignee: none
Date: 10/13/1992
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Abstract>US Patent: 5,155,708
Title: Acoustic Wave Sensor and Method of Making Same
Inventors: Ram L. Bedi and Alan R. Selfridge
Assignee: none
Date: 10/13/1992A hydrophone for calibrating lithotriptors including a spot poled disc of piezoelectric material which is mounted on a brass cylinder backing. A coaxial cable is electrically connected to one surface of the disc through the brass backing and the opposing surface of the disc. A mixture of polymetric materials and microbaloons is provided to protect the interconnection of the center conductor and the opposing surface of the disc and prevent damage due to the incident ultrasonic shock waves. The brass backing is placed in a suitable housing of phenolic material. A process in fabricating the piezoelectric disc and assembling the hydrophone is disclosed.
- 5,134,988
Title: Lens Assembly for Focusing Energy
Inventors: J. Pell, G. Hansen, W. Stephens and A. Selfridge
Assignee: Diasonic Inc.
Date: 08/04/1992
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Abstract>US Patent: 5,134,988
Title: Lens Assembly for Focusing Energy
Inventors: James W. Pell, Gerald L. Hansen, William H. Stephens and Alan R. Selfridge
Assigned: Diasonics, Inc.
Date: 08/04/1992An acoustical lens for focusing ultrasonic energy having a transducer, a curved focusing lens and a voltage generator coupled with the transducer. The transducer is comprised of an array of piezoelectric crystal elements. The focusing lens has a concave upper surface and a planar bottom surface allowing the array of piezoelectric elements to be coupled to the bottom surface of the array. The piezoelectric elements receive voltage from the voltage generator and transmit an energy ray through the focusing lens producing a focused energy beam.
- 5,107,233
Title: Amplitude Correction of Field Coupled Varactor Tuned FIlters
Inventors: D. Stoft
Assignee: Hewlett-Packard Company
Date: 04/21/1992
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Abstract>US Patent: 5,107,233
Title: Amplitude Correction of Field Coupled Varactor Tuned Filters
Inventors: David E. Stoft
Assignee: Hewlett-Packard Company
Date: 04/21/1992In a multi-stage, varactor-tuned bandpass filter utilizing electromagnetic field coupling between successive filter stages, the effective area of a coupling window provided in the RF shielding separating the filter stages is varied as a function of the varactor tune voltage to provide a flat frequency response over the filter frequency range. The bias current through a PIN diode connected across the coupling window is controlled by varactor tune voltage to effectively decrease the window area with increasing filter frequency.
- 5,059,892
Title: Radio Frequency Signal Interface
Inventors: D. Stoft
Assignee: Hewlett-Packard Company
Date: 10/22/1991
[PDF 1.2MB]
Abstract>US Patent: 5,059,892
Title: Radio Frequency Signal Interface
Inventors: David E. Stoft
Assignee: Hewlett-Packard Company
Date: 10/22/1991A multi-function, general purpose apparatus includes various instrument modules configured to perform a number of functions controlled by an internal processor, stored programs and user selected inputs. A five-port RF signal interface couples the apparatus to user equipment under test to allow a wide range of RF signal levels. The RF signal interface buffers the user equipment from the apparatus internal modules while providing a uniform attenuation of an RF test signal over the RF path to the desired internal module. Antenna, RF Input and Duplex ports provide apparatus connection to user equipment while signal generator and receiver ports provide internal apparatus connections. An apparatus internal processor is user and software controlled to provide automatic sweep tuning of RF interface filter sections and automatic sensitivity settings for the interface amplifier and attenuator sections. A preferred embodiment of the invention includes a multi-function general purpose test system particularly adapted to the testing and measuring of signals to and from RF apparatus.
- 5,033,456
Title: Acoustical Lens Assembly for Focusing Ultrasonic Energy
Inventors: J. Pell, G. Hansen, W. Stephens and A. Selfridge
Assignee: Diasonic Inc.
Date: 07/23/1991
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Abstract>US Patent: 5,033,456
Title: Acoustical Lens Assembly for Focusing Ultrasonic Energy
Inventors: James W. Pell, Gerald L. Hansen, William H. Stephens and Alan R. Selfridge
Assigned: Diasonics, Inc.
Date: 07/23/1991An acoustical lens for focusing ultrasonic energy having a transducer, a curved focusing lens and a voltage generator coupled with the transducer. The transducer is comprised of an array of piezoelectric crystal elements. The focusing lens has a concave upper surface and a planar bottom surface allowing the array of piezoelectric elements to be coupled to the bottom surface of the array. The piezoelectric elements receive voltage from the generator and transmit an energy ray through the focusing lens producing a focused energy beam.
- 4,917,097
Title: Apparatus and Method for Imaging Small Cavities
Inventors: A. Proudian, M. Ebherle, A. Savakus, H. Kiepen, D. Stephens, D. Rammler and C. Zanelli
Assignee: Endosonics Corporation
Date: 04/17/1990
[PDF 2.4MB]
Abstract>US Patent: 4,917,097
Title: Apparatus and Method for Imaging Small Cavities
Inventors: Andrew P. Proudian, Michael J. Eherle, Adam D. Savakus, Horst F. Kiepen, Douglas N. Stephens, David H. Rammler, and Claudio I. Zanelli
Assignee: Endosonics Corporation
Date: 04/17/1990An in vivo imaging device is provided for producing real-time images of small, moving or stationary cavities and surrounding tissue structure. The imaging device includes a probe assembly of very small dimensions and preferably sufficiently small to fit within cavities having a diameter on the order of that of a human coronary atery. The probe assembly may be mounted to a positioning device such as a catheter, which allows for the use of, for example, conventional guiding catheters and guide wires.
- 4,887,606
Title: Apparatus for use in Cannulation of Blood Vessels
Inventors: P. Yock and A. Selfridge
Assignee: none
Date: 12/19/1989
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Abstract>US Patent: 4,887,606
Title: Apparatus for use in Cannulation of Blood Vessels
Inventors: Paul G. Yock, and Alan R. Selfridge
Assignee: None
Date: 12/19/1989Apparatus for use in cannulation of blood vessels includes a hollow needle having a sharpened end for penetrating tissue, a trocar including a transducer mounted on one end for positioning within the hollow needle for transmitting and receiving ultrasonic waves through the sharpened end of the needle. The trocar further includes a support rod for the transducer and ultrasound damping material attaching the transducer to the support rod. Electrical conductors are provided through the support rod or on the surface of the support rod in contact with electrodes on the front and back surfaces of the transducer for transmitting electrical signals to and from the transducer. A syringe portion is detachably detached from the needle for receiving the back flow of blood when the needle is inserted into a blood vessel.
- 4,612,809
Title: Curved-Array Ultrasonic Probe Using Low-Velocity Fluid
Inventors: R. Cribbs and C. Zanelli
Assignee: Sound Products Company
Date: 09/23/1986
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Abstract>US Patent: 4,612,809
Title: Curved-Array Ultrasonic Probe Using Low-Velocity Fluid
Inventors: Robert W. Cribbs, and Claudio I. Zanelli
Assignee: Sound Products Company, L.P.
Date: 09/23/1986A small, simple, yet accurate probe for producing a sector scan for ultrasonic medical diagnostic apparatus is provided by positioning a curved transducer array within the probe opposite a window, and filling the probe with a fluid having an acoustic velocity on the order of 0.5x10^5 cm/sec. This combination is made possible by forming the window from a stiff polyionomer material whose acoustic velocity is close to that of human skin, yet which is stiff enough when thin to be essentially non-deformable in clinical use. Grating lobes of the ultrasonic beam, as well as the scatter produced within the probe by the high reflectivity of the window material, are absorbed by coating or lining the inner side walls of the probe with an open-celled polyether urethane foam having a cell diameter slightly smaller than one wavelength of the ultrasound in the probe fluid.
- 4,528,652
Title: Ultrasonic Transducer and Attenuating Material for use Therein
Inventors: M. Horner, A. Brisken and C. Zanelli
Assignee: General Electric Company
Date: 07/09/1985
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Abstract>US Patent: 4,528,652
Title: Ultrasonic Transducer and Attenuating Material for use Therein
Inventors: Michael S. Horner, Axel F. Brisken, and Claudio I. Zanelli
Assignee: General Electric Company
Date: 07/09/1985
An improved material for an ultrasonic transducer assembly having improved noise supression characteristics comprising an ultrasonic transducer having a plurality of surfaces, a housing for receiving said transducer whereby one surface of said transducer is free to transmit and receive ultrasonic waves, and a material positioned about said transducer and beterrn said transducer and the environment or housing for attenuating ultrasonic energy, said material comprising a heavily loaded resin based on an unfilled low viscosity potting gel and a filler selected from the group consisting of heavy oxides, metal powders, and density lowering fillers. In specific embodiments lead oxide, tungsten powder, and glass microspheres have been used as the filler in a silicone or flexible epoxy.