Patent US3736423A successfully refreshed from Google Patents.
US3736423A
Expired / Lapsed
US
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Electron lens of magnetic field type for an electron microscope and the like
Assignee: Hitachi Ltd
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Filing: 1971-05-12
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Granted: 1973-05-29
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Expires: 1991-05-12
Abstract
Abstract An electron lens of the magnetic field type, wherein a plurality of compensating coils are installed in a magnetic cover for a lens coil and wherein compensating currents are supplied to said compensating coils, whereby astigmatism appearing in the lens and undesired deflection of an electron beam passing through the lens are compensated by adjusting said currents.
Inventors
- 👤 S Katagiri
- 👤 S Kasai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:36
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/153; H01J37/10; H01J37/14
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
112 words
In an electron lens of the magnetic field type for an electron microscope and the like, comprising an exciting lens coil wound in an annular shape, a magnetic cover disposed to cover said lens coil and composed of an upper magnetic path member, a lower magnetic path member and upper and lower magnetic pole pieces, the improvement which comprises a plurality of compensating coils each being wound on different portions of said magnetic cover through holes provided therein, supply means for supplying compensating currents to said compensating coils and adjusting means for adjusting said compensating currents whereby astigmatism and undesired deflection of an electron beam passing through said lens can be eliminated.
Claim 2
Dependent Claim
112 words
In an electron lens of the magnetic field type for an electron microscope and the like, comprising an exciting lens coil wound in an annular shape, a magnetic cover disposed to cover said lens coil and composed of an upper magnetic path member, a lower magnetic path member and upper and lower magnetic pole pieces, the improvement which comprises a plurality of compensating coils each being wound on different portions of said magnetic cover through holes provided therein, supply means for supplying compensating currents to said compensating coils and adjusting means for adjusting said compensating currents whereby astigmatism and undesired deflection of an electron beam passing through said lens can be eliminated.
Claim 3
Dependent Claim
30 words
An electron lens according to claim 1, characterized by eight compensating coils, which are respectively arranged such that the central axes of adjacent coils define an angle of 45* therebetween.
Claim 4
Dependent Claim
19 words
An electron lens according to claim 1, characterized in that said compensating coils are embedded in said magnetic cover.
Claim 5
Dependent Claim
39 words
An electron lens according to claim 1, characterized by four compensating coils, the central axes of one pair of coils opposing each other defining an angle of 45* with those of the other pair of coils opposing each other.
Claim 6
Dependent Claim
19 words
An electron lens according to claim 1, wherein said compensating coils are provided in said lower magnetic path member.
Claim 7
Dependent Claim
20 words
An electron lens according to claim 5, wherein said compensating coils are disposed symmetrically about said lower magnetic pole piece.
Claim 8
Dependent Claim
19 words
An electron lens according to claim 1, wherein said compensating coils are disposed around said lower magnetic pole piece.
Claim 9
Dependent Claim
40 words
An electron lens according to claim 7, wherein said upper and lower magnetic pole pieces define a central passage and an insulating tube is disposed in said central passage formed by said lower pole piece to protect said compensating coils.
Claim 10
Dependent Claim
40 words
An electron lens according to claim 1, wherein said upper and lower pole pieces form a magnetic lens gap therebetween, said compensating coils being disposed in said lower magnetic path member in a plane substantially passing through said lens gap.
Claim 11
Dependent Claim
30 words
An electron lens according to claim 9, wherein four compensating coils are provided in said lower magnetic path member so as to occupy a respective quadrant about said lens gap.
Claim 12
Dependent Claim
33 words
An electron lens according to claim 1, wherein said compensating coils are wound in planes parallel to the axis of said lens coil adjacent a passage through said upper and lower pole pieces.
Claim 13
Dependent Claim
39 words
An electron lens according to claim 11, characterized by four compensating coils, the central axes of one pair of coils opposing each other defining an angle of 45* with those of the other pair of coils opposing each other.
References Cited (Backward Citations)
US3046397A
Cited
US3150258A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-28 | 1976-11-27 | 1977-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-28 | 1980-11-27 | 1981-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-28 | 1984-11-27 | 1985-05-29 | $7700.00 | Window Closed / Lapsed |