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US 4,366,406 AGranted
Ultrasonic transducer for single frequency applications
AssigneeGeneral Electric Company
InventorsLowell S. Smith, Axel F. Brisken
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Abstract
An ultrasonic transducer has two impedance matching layers bonded to the transducer element which have different thicknesses and are 90.degree.-100.degree. and 35.degree.-55.degree. matching layers. This structure has a high sensitivity comparable to a broadband front surface matched transducer with quarter wavelength (90.degree. and 90.degree.) matching layers, and has primarily a single resonant mode so as to be suitable for relatively narrow band applications.
Claims6
An ultrasonic transducer for single frequency applications comprising:
- a front surface matched transducer comprising at least one transducer element to which are bonded first and second impedance matching layers that serve as acoustic transformers to match the high acoustic impedance of said element to the low acoustic impedance of the human body or water;
- said first matching layer having a thickness proportional to 90/360 to 100/360 wavelength and said second matching layer next to said element having a thickness proportional to 35/360 to 55/360 wavelength, both at a given nominal reference frequency of operation;
- said front surface matched transducer having a narrow band frequency spectrum and high sensitivity.
An ultrasonic transducer for single frequency applications comprising:
- a front surface matched linear transducer array comprising plural transducer elements which are acoustically uncoupled and to each of which are bonded first and second impedance matching layers that serve as acoustic transformers to match the high acoustic impedance of said elements to the low acoustic impedance of the human body or water;
- said first matching layer having a thickness ##EQU5## and said second matching layer having a thickness ##EQU6## where Z.sub.1 and Z.sub.2 are the acoustic impedances of said first and second layers, P.sub.1 and P.sub.2 are the densities of said first and second layers, and f is the nominal reference frequency of operation;
- said front surface matched array having a narrow band frequency spectrum and high sensitivity.
Dependencies are inferred from the claim text.