Patent US3629578A successfully refreshed from Google Patents.
US3629578A
Expired / Lapsed
US
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Magnetic deflection system for electron analysis devices
Assignee: US Philips Corp
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Filing: 1969-01-27
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Granted: 1971-12-21
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Expires: 1989-01-27
Abstract
Abstract A magnetic deflecting system for deflecting a beam of charged particles comprising a pair of mirror symmetrical pole-pieces on opposite sides of a plane of symmetry passing through a principal ray of the beam. The surfaces of the pole-pieces have contours which define a space between the pole-pieces which varies stepwise in the direction of the main ray with a centrally constricted portion which defines a region of highest field strength. The deflection system has a field strength at which the main ray entering the deflection system, which ray extends at least partly in the direction of the constricted space between the pole-pieces, follows a curve which passes in front of the pole-pieces in the region of the highest magnetic field strength. Means are provided to produce a field strength distribution at the area of the minimum distance of the curve from the region of the highest field strength which, measured in the direction towards the highest field strength, exhibits at that area a locally stronger field strength gradient. This field strength distribution affects the beam so that a curvature of image lines transverse to the plane of symmetry in a plane transverse to the main ray is counteracted, i.e., electron-optical aberrations are reduced.
Inventors
- 👤 Jan B Le Poole
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:02
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/147; H01J29/00; H01J29/46; H01J29/70; H01J29/72; H01J29/76; H01J37/10; H01J37/14; H01J37/153; H01J37/252; H01J37/26; H01J37/29
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
217 words
A device for deflecting a beam of charged particles including a magnetic deflection system having a plane of symmetry passing through a main ray of said beam comprising two mirror symmetrical magnet poles disposed on opposite sides of said plane of symmetry, the opposing surfaces of the poles having contours which define a space therebetween which varies stepwise in the direction of said main ray with a central portion having a constricted cross section defining a region of highest magnetic field strength, said deflection system having a strength at which the main ray of the beam entering the deflection system, which ray extends at least partly in the direction of constriction of the space between the pole faces, follows a curve therebetween, which curve passes between the pole-faces in the region of the highest magnetic field strength, and at the area at which the distance of said curve from the region of the highest magnetic field strength is shortest a field strength distribution which, measured in the direction towards the region of the highest magnetic field strength, exhibits at said area a locally stronger field strength gradient, which field strength distribution affects the beam so that a curvature of image lines transverse to the plane of symmetry in a plane transverse to the main ray is counteracted.
Claim 2
Independent Claim
217 words
A device for deflecting a beam of charged particles including a magnetic deflection system having a plane of symmetry passing through a main ray of said beam comprising two mirror symmetrical magnet poles disposed on opposite sides of said plane of symmetry, the opposing surfaces of the poles having contours which define a space therebetween which varies stepwise in the direction of said main ray with a central portion having a constricted cross section defining a region of highest magnetic field strength, said deflection system having a strength at which the main ray of the beam entering the deflection system, which ray extends at least partly in the direction of constriction of the space between the pole faces, follows a curve therebetween, which curve passes between the pole-faces in the region of the highest magnetic field strength, and at the area at which the distance of said curve from the region of the highest magnetic field strength is shortest a field strength distribution which, measured in the direction towards the region of the highest magnetic field strength, exhibits at said area a locally stronger field strength gradient, which field strength distribution affects the beam so that a curvature of image lines transverse to the plane of symmetry in a plane transverse to the main ray is counteracted.
Claim 3
Dependent Claim
67 words
A device as claimed in claim 1 wherein at a distance from the region of the highest field strength corresponding with the shortest distance between this region and the main ray of the beam the pole faces have a steplike profile so that the space between the two pole faces, viewed in the direction towards the region of the highest field strength, exhibits a substantially abrupt constriction.
Claim 4
Dependent Claim
102 words
A device as claimed in claim 1 wherein the magnet poles are electromagnetically energized and are formed by spaced concentric sections, which are energized differently and are located one after the other in the direction towards the region of the highest magnetic field strength in the field space and separated from each other by a narrow ferromagnetism-free gap at the area of the pole face formed by the common ends of said sections, one of said gaps being located at a distance from the region of the highest field strength corresponding to the shortest distance between said region and said main ray.
Claim 5
Dependent Claim
45 words
A device as claimed in claim 1 wherein the portion of the plane of symmetry lying between the pole faces the magnetic field strength is mainly inversely proportional to the distaNce from the region where the planes mainly defining the pole faces intersect each other.
Claim 6
Dependent Claim
31 words
A device as claimed in claim 1 wherein the opposite faces of the poles are located in planes of revolution having an axis of revolution transverse to the plane of symmetry.
Claim 7
Dependent Claim
37 words
A device as claimed in claim 5 wherein the pole faces are mainly located in conical planes of revolution having their vertices at the point of intersection of the axis of revolution with said plane of symmetry.
Claim 8
Dependent Claim
33 words
A device as claimed in claim 6, wherein the region of locally stronger fieLd strength gradient is located approximately midway between the outer peripheries of the pole faces and the axis of revolution.
Claim 9
Dependent Claim
75 words
In an electron microscope including an electron beam source, an objective lens, a projection lens, and a target member positioned to intercept the electron beam, the improvement comprising a deflection system as claimed in claim 1 is arranged after the objective and which deflects the electron beam through an angle of more than 90* , the electron beam emanating from the deflection system being directed to a target member for reproducing or recording the image.
Claim 10
Dependent Claim
91 words
A device as claimed in claim 8 comprising two target members, at least one of which is equipped with a luminescent screen for displaying the image, said target members being arranged in the plane of symmetry of the deflection system on either side of the beam directed to the deflection system, and means for changing over the beam from one target member to the other by reversing the magnetic field in the field space of the deflection system and by shifting the plane of the beam directed to the deflection system.
Claim 11
Dependent Claim
69 words
In an X-ray analyzer comprising an electron beam source and means to focus the electron beam onto an object to be examined, the improvement comprising a deflection system as claimed in claim 5 arranged near the focus of a hollow electron mirror, a collimated electron beam being deflected and directed to the electron mirror, which focuses the beam onto the object disposed in the vicinity of the deflection system.
References Cited (Backward Citations)
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US3287558A
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US3229087A
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US3243667A
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US3398385A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |