US3702398A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron beam apparatus
Assignee: Cambridge Scientific Instruments Ltd
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Filing: 1971-01-21
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Granted: 1972-11-07
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Expires: 1991-01-21
Abstract
Abstract In electron probe apparatus modified or designed to display electron-channelling (pseudo-Kikuchi) effects by subjecting a point on a specimen surface to an electron beam scanned through a varying angle, the final lens of the beam forming system is employed as a deflection element in that an image of the source is formed in the plane of deflection means and that this plane and the specimen surface are made conjugate points with respect to the final lens. To facilitate corrections for spherical aberration in the scanning, the scanning is preferably performed on polar co-ordinates, with the beam sweeping out a conical path of slowly varying cone angle, and the result is displayed as a spirally scanned image.
Inventors
- 👤 Christopher Geoffrey Van Essen
- 👤 Erland Maxwell Schulson
- 👤 Richard Hugh Donaghay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:36
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/153; H01J37/147; H01J37/1478; H01J37/26; H01J37/28
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
292 words
Electron probe apparatus comprising a source of electrons, beam forming means, said beam-forming means forming a beam from said electrons along an axis and forming an image of said source at a first point spaced along said axis from said source, first beam-deflection means, said deflection means being effective on said axis at said first point, means feeding a saw-tooth deflection signal to said beam-deflecting means whereby to cause said beam to be deflected back and forth laterally from said axis in an angular manner centered on said first point, means defining an aperture around said axis at a second point on said axis further from said source than said first point, electron lens means disposed around said aperture and serving to focus said beam to a spot at a third point on said axis, said third point being farther from said source than said first and second points, said electron lens serving simultaneously to deflect said beam back towards said axis in dependence on the departure of said beam from said axis whereby said electron lens simultaneously forms second beam-deflection means causing said spot to remain substantially on said axis as said beam is scanned back and forth by said first beam-deflection means so that said beam effectively rocks angularly about said third point in step with said sawtooth deflection signal, means for locating a specimen surface at said third point, detector means adapted to detect the response at said specimen surface to the impact of said beam, and display means connected to said detector means and said saw-tooth deflection signal feeding means to produce a visual display of the response of said detector means in accordance with the angular variation of the impact of the beam on said specimen surface.
Claim 2
Dependent Claim
292 words
Electron probe apparatus comprising a source of electrons, beam forming means, said beam-forming means forming a beam from said electrons along an axis and forming an image of said source at a first point spaced along said axis from said source, first beam-deflection means, said deflection means being effective on said axis at said first point, means feeding a saw-tooth deflection signal to said beam-deflecting means whereby to cause said beam to be deflected back and forth laterally from said axis in an angular manner centered on said first point, means defining an aperture around said axis at a second point on said axis further from said source than said first point, electron lens means disposed around said aperture and serving to focus said beam to a spot at a third point on said axis, said third point being farther from said source than said first and second points, said electron lens serving simultaneously to deflect said beam back towards said axis in dependence on the departure of said beam from said axis whereby said electron lens simultaneously forms second beam-deflection means causing said spot to remain substantially on said axis as said beam is scanned back and forth by said first beam-deflection means so that said beam effectively rocks angularly about said third point in step with said sawtooth deflection signal, means for locating a specimen surface at said third point, detector means adapted to detect the response at said specimen surface to the impact of said beam, and display means connected to said detector means and said saw-tooth deflection signal feeding means to produce a visual display of the response of said detector means in accordance with the angular variation of the impact of the beam on said specimen surface.
Claim 3
Dependent Claim
46 words
Electron probe apparatus as set forth in claim 1 including means supplying a correcting signal to said electron lens, said correcting signal being variable in synchronism with said first beam-deflecting means and serving to correct the path of said beam for spherical aberration of said lens.
Claim 4
Dependent Claim
32 words
Electron probe apparatus as set forth in claim 2 wherein said first beam-deflecting means are such as to cause said beam to sweep out a conical path of slowly varying cone angle.
Claim 5
Dependent Claim
25 words
Electron probe apparatus as set forth in claim 3 wherein said display means are such as to produce a two-dimensional display by a spiral scan.
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) | 1975-11-07 | 1976-05-08 | 1976-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-07 | 1980-05-08 | 1980-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-07 | 1984-05-08 | 1984-11-07 | $7700.00 | Window Closed / Lapsed |