Patent US3754208A successfully refreshed from Google Patents.
US3754208A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compound lens for converting the effect of large-area sonic transducer to one of small area
Assignee: SRI International Inc
•
Filing: 1972-02-03
•
Granted: 1973-08-21
•
Expires: 1992-02-03
Abstract
Abstract A compound lens structure for converting the response of a transducer of large lateral extent to one of significantly smaller dimensions employs a converting lens having a conical front surface in contact with the rear surface of an auxiliary hemispherical lens to allow spherical sonic waves emanating from or converging toward the point of contact to enter or leave the converting lens only through the area of contact. The rear surface of the converting lens is chosen to be a hyperbola of revolution in order that diverging waves entering through the area of contact be refracted into plane waves transmitted to the transducer. Space between the two lens is sealed and filled with a gas to enhance the masking effect of the conical surface by total reflection of waves entering that sealed space from the auxiliary lens.
Inventors
- 👤 G Eilers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:41
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/18; G10K11/26; G10K11/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
220 words
A compound lens structure, for converting the effect of a large-area sonic transducer in a liquid to one of significantly smaller area, comprised of a converting lens having a rear surface facing said transducer, said rear surface being in the form of a hyperbola of revolution, where the axis of revolution passes through the focus of the hyperbola, and a front surface in the form of a cone over said rear surface with its axis along said axis of revolution, whereby sonic waves emerging from said lens through a region of said front surface at the apex of said cone are in the form of diverging spherical waves as though said region were a sonic wave point source while substantially plane waves are transmitted by said transducer into said rear surface, an auxiliary lens having a rear surface acoustically coupled to said conical front surface of said converting lens over a small area at the apex thereof with material having a plane wave velocity substantially the same as the material of said converting lens, thereby defining said region through which sonic waves emerge from said converting lens and enter said auxiliary lens, and means for sealing a space devoid of liquid or solid material between said rear surface of said auxiliary lens and said front surface of said converting lens.
Claim 2
Dependent Claim
220 words
A compound lens structure, for converting the effect of a large-area sonic transducer in a liquid to one of significantly smaller area, comprised of a converting lens having a rear surface facing said transducer, said rear surface being in the form of a hyperbola of revolution, where the axis of revolution passes through the focus of the hyperbola, and a front surface in the form of a cone over said rear surface with its axis along said axis of revolution, whereby sonic waves emerging from said lens through a region of said front surface at the apex of said cone are in the form of diverging spherical waves as though said region were a sonic wave point source while substantially plane waves are transmitted by said transducer into said rear surface, an auxiliary lens having a rear surface acoustically coupled to said conical front surface of said converting lens over a small area at the apex thereof with material having a plane wave velocity substantially the same as the material of said converting lens, thereby defining said region through which sonic waves emerge from said converting lens and enter said auxiliary lens, and means for sealing a space devoid of liquid or solid material between said rear surface of said auxiliary lens and said front surface of said converting lens.
Claim 3
Dependent Claim
35 words
A compound lens structure as defined in claim 1 wherein said auxiliary lens has a hemispherical front surface with its center at the center of said rear surface area acoustically coupled to said converting lens.
Claim 4
Dependent Claim
41 words
A compound lens structure as defined in claim 2 wherein said rear surface of said auxiliary lens is acoustically coupled to said conical surface of said converting lens by a cylindrical tip formed as an integral part of said converting lens.
Claim 5
Dependent Claim
59 words
A compound lens structure as defined in claim 3 wherein the cone angle of said conical front surface is arbitrarily chosen from a range between a maximum approaching 180* and a minimum cone angle which would produce a conical surface cutting through a region between said rear surface and asymptotes to the hyperbola of revolution forming said rear surface.
Claim 6
Dependent Claim
100 words
A compound lens structure as defined in claim 4 wherein a line drawn normal to one of said asymptotes in a plane passing through said asymptote and axis of revolution for said rear surface of said converting lens defines an angle with said axis which is a critical angle theta c for transmission of sound through said rear surface of said converting lens, where said angle theta c bears the relation sin theta c VL Divided by VS to the plane wave velocity VL in said liquid and the plane wave velocity VS in the material of said converting lens.
References Cited (Backward Citations)
US2972068A
Cited
US3295629A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-20 | 1977-02-19 | 1977-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-20 | 1981-02-19 | 1981-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-20 | 1985-02-19 | 1985-08-21 | $7700.00 | Window Closed / Lapsed |