US3707628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic lenses
Assignee: National Research Development Corp UK
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Filing: 1971-03-22
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Granted: 1972-12-26
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Expires: 1991-03-22
Abstract
Abstract A magnetic lens, for focusing a beam of charged particles, includes a coil at least part of which, at an end thereof, tapers conically with a half-angle between 20* and 85*. The coil may comprise a plurality of conductors laid concurrently, and cooling means may be provided in contact with the inner surface. Desirably, the coil is shrouded, at least in part, with material of high magnetic permeability. Radiation such as X-rays, from a target in focus beyond the tapering end of the coil, may be detected over a large solid angle.
Inventors
- 👤 Richard Bassett
- 👤 Thomas Mulvey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:39
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/10; H01J37/14; H01J37/141
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
159 words
An electromagnetic lens for focusing a beam of charged particles, said lens comprising: a coil wound with a plurality of separate concurrently laid lengths of electrically conducting wire said lengths extending from one axial end of said coil to the other axial end thereof with the ends of the separate lengths being uniformly distributed around the circumference of said coil whereby substantial circumferential magnetic field uniformity is insured by electrical interconnections of said separate lengths with each other and with a source of electrical current, said coil having two open substantially magnetically unshrouded ends and an inner and an outer surface, at least an end part of which is substantially frusto-conical in shape tapering towards one unshrouded end of the coil with a half conical angle lying between 20* and 75*, said frusto-conical shape causing an increased magnetic field intensity towards said one unshrouded end of the coil to result in focussing an axially directed beam of charged particles.
Claim 2
Dependent Claim
159 words
An electromagnetic lens for focusing a beam of charged particles, said lens comprising: a coil wound with a plurality of separate concurrently laid lengths of electrically conducting wire said lengths extending from one axial end of said coil to the other axial end thereof with the ends of the separate lengths being uniformly distributed around the circumference of said coil whereby substantial circumferential magnetic field uniformity is insured by electrical interconnections of said separate lengths with each other and with a source of electrical current, said coil having two open substantially magnetically unshrouded ends and an inner and an outer surface, at least an end part of which is substantially frusto-conical in shape tapering towards one unshrouded end of the coil with a half conical angle lying between 20* and 75*, said frusto-conical shape causing an increased magnetic field intensity towards said one unshrouded end of the coil to result in focussing an axially directed beam of charged particles.
Claim 3
Dependent Claim
32 words
An electromagnetic lens as in claim 1 further including: a plurality of annular conducting sections at each end of said coil for making external electrical connections to said separate lengths of wire.
Claim 4
Dependent Claim
37 words
An electromagnetic lens as in claim 1 further including: return conductor means disposed substantially parallel to a geometrical generator of said frusto-conical coil end for providing an external electrical connection to the small end of said coil.
Claim 5
Dependent Claim
25 words
An electromagnetic lens as in claim 1 wherein said separate lengths of conducting wires are all laid in the same axial sense around said coil.
Claim 6
Dependent Claim
49 words
An electromagnetic lens as in claim 1 wherein said plurality of lengths comprises an even number whereby alternate lengths can be electrically connected in parallel to form two such parallel circuits which, in turn, may be connected in series with each other to help insure circumferentially uniform current distributions.
Claim 7
Dependent Claim
19 words
An electromagnetic lens as in claim 1 in which the half conical angle lies between 30* and 60* .
Claim 8
Dependent Claim
20 words
An electromagnetic lens as in claim 1 in which the coil is cooled by means located on its inner surface.
Claim 9
Dependent Claim
51 words
An electromagnetic lens as in claim 1 wherein said coil is constructed to have a radial depth as measured between the inner and outer surfaces of the coil winding is not more than one-fifth of the dimension of the coil in the direction of a generator of the frusto-conical coil surface.
Claim 10
Dependent Claim
33 words
An electromagnetic lens as in claim 1 in which the coil is enclosed on the outer surface only thereof, at least in part, by a shroud consisting of material of high magnetic permeability.
Claim 11
Dependent Claim
63 words
An electromagnetic lens as in claim 1 wherein said coil is constructed to cause the distance between the points at which the field strength on the axis of the lens has half its maximum value is large compared with the distance from the smaller end of the lens to the location at which a beam of charged particles is focused by the lens.
Claim 12
Independent Claim
198 words
An apparatus for analyzing an object of which comprises: a source for producing a beam object charged particles which is directed onto said object, a detector for detecting characteristic radiation emitted from said object, and a magnetic lens for focusing said beam of charged particles onto said object, the magnetic lens comprising; a coil wound with a plurality of separate concurrently laid lengths of electrically conducting wire said lengths extending from one axial end of said coil to the other axial end thereof with the ends of the separate lengths being uniformly distributed around the circumference of said coil whereby substantial circumferential magnetic field uniformity is insured by electrical interconnections of said separate lengths with each other and with a source of electrical current, said coil having two open substantially magnetically unshrouded ends and an inner and an outer surface, at least an end part of which is substantially frusto-conical in shape tapering towards one unshrouded end of the coil with a half conical angle lying between 20* and 75*, said frusto-conical shape causing an increased magnetic field intensity towards said one unshrouded end of the coil to result in focussing an axially directed beam of charged particles.
Claim 13
Independent Claim
198 words
An apparatus for analyzing an object of which comprises: a source for producing a beam object charged particles which is directed onto said object, a detector for detecting characteristic radiation emitted from said object, and a magnetic lens for focusing said beam of charged particles onto said object, the magnetic lens comprising; a coil wound with a plurality of separate concurrently laid lengths of electrically conducting wire said lengths extending from one axial end of said coil to the other axial end thereof with the ends of the separate lengths being uniformly distributed around the circumference of said coil whereby substantial circumferential magnetic field uniformity is insured by electrical interconnections of said separate lengths with each other and with a source of electrical current, said coil having two open substantially magnetically unshrouded ends and an inner and an outer surface, at least an end part of which is substantially frusto-conical in shape tapering towards one unshrouded end of the coil with a half conical angle lying between 20* and 75*, said frusto-conical shape causing an increased magnetic field intensity towards said one unshrouded end of the coil to result in focussing an axially directed beam of charged particles.
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) | 1975-12-26 | 1976-06-26 | 1976-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-26 | 1980-06-26 | 1980-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-26 | 1984-06-26 | 1984-12-26 | $7700.00 | Window Closed / Lapsed |