US3818394A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron lens for electron microscope and the like
Assignee: Hitachi Ltd
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Filing: 1967-06-09
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Granted: 1974-06-18
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Expires: 1987-06-09
Abstract
Abstract An electron lens assembly having a diamagnetic shielding member or members inserted in the central opening of a hollow, cylindrical superconducting coil, at least one of the members is movable therein along the axis of the electron beam whilst the coil and member or members are kept in a superconducting state. By this arrangement, the focal length of the lens assembly can be changed by the variation along the axis of the coil of the distribution of magnetic field strength produced by the coil.
Inventors
- 👤 H Kimura
- 👤 T Doi
- 👤 S Katagiri
- 👤 S Ozasa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:51
CPC Classifications
H; H01; H01F; H01F6/00; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/10; H01J37/14; H01J37/141; H01J37/1416; H01J37/147; H01J37/15; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/871
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
73 words
An electron lens assembly comprising a coil formed from superconducting material and defining a central opening the center axis of which is designed for alignment with an electron beam path, at least one shielding diamagnetic member supported within the central opening of the coil and surrounding the center axis thereof, means for moving the diamagnetic member relative to the coil, and means for maintaining said coil and said member in a superconducting state.
Claim 2
Dependent Claim
73 words
An electron lens assembly comprising a coil formed from superconducting material and defining a central opening the center axis of which is designed for alignment with an electron beam path, at least one shielding diamagnetic member supported within the central opening of the coil and surrounding the center axis thereof, means for moving the diamagnetic member relative to the coil, and means for maintaining said coil and said member in a superconducting state.
Claim 3
Dependent Claim
30 words
An electron lens assembly according to claim 1 wherein said diamagnetic member is axially movable along the center axis of the coil for adjusting the focal length of lens assembly.
Claim 4
Dependent Claim
23 words
An electron lens assembly according to claim 2 wherein the diamagnetic member is symmetrically-shaped with respect to the center axis of the coil.
Claim 5
Dependent Claim
53 words
An electron lens assembly according to claim 1 wherein there are at least two shielding diamagnetic members, one supported at each end of the central opening of the coil and surrounding the center axis thereof, at least one of the diamagnetic members being axially movable relative to the center axis of the coil.
Claim 6
Dependent Claim
28 words
An electron lens assembly according to claim 4 wherein the coil and central opening are cylindrically-shaped and the shielding diamagnetic members are symmetrically-shaped relative to the center axis.
Claim 7
Dependent Claim
82 words
An electron lens assembly according to claim 5 further including an annular magnetizable core member having a U-shaped cross section surrounding said coil and having the center axis thereof aligned with the center axis of the coil, one of said shielding diamagnetic members being secured to one side of the central opening in the annular core member and the other shielding diamagnetic member being movably supported on the remaining side, and a reservoir of superconducting refrigerant surrounding said annular magnetizable core member.
Claim 8
Dependent Claim
70 words
An electron lens assembly according to claim 6 wherein the movable shielding diamagnetic member comprises an open ended cylindrically-shaped member having its center axis aligned with the center axis of the coil and having a rack formed on one end thereof, a pinion coacting with the rack on the diamagnetic member, and means for movably supporting the shielding diamagnetic member on the annular magnetizable core member in axial alignment therewith.
Claim 9
Dependent Claim
34 words
An electron lens assembly according to claim 7 wherein the movable supporting means comprises a thermally conductive flexible metal foil secured between the annular magnetizable core member and the cylindrically-shaped movable diamagnetic shielding member.
Claim 10
Dependent Claim
85 words
An electron lens assembly according to claim 7 wherein the movable supporting means comprises a flexible bellows filled with superconducting refrigerant from the reservoir and wherein the reservoir surrounds the entire assembly with the exceptiOn of a central open passageway coaxially aligned with the center axis of the coil and in alignment with the electron beam path and with the exception of the rack portion of the movable diamagnetic shielding member, the bellows being secured between said rack portion and the walls of the reservoir.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-17 | 1977-12-17 | 1978-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-17 | 1981-12-17 | 1982-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-17 | 1985-12-17 | 1986-06-18 | $7700.00 | Window Closed / Lapsed |