Wien filter
First Claim
1. An electric device, comprising:
- twelve electrodes, inner ends of said twelve electrodes configuring a cylindrical through hole and an 8-fold symmetry, twelve through slits separating the twelve electrodes respectively and parallel to a central axis of said hole, said central axis being an optical axis of the electric device,wherein each of said twelve through slits has a central plane containing the optical axis,wherein a 1st electrode, a 2nd electrode, a 3rd electrode, a 4th electrode, a 5th electrode, a 6th electrode, a 7th electrode, an 8th electrode, a 9th electrode, a 10th electrode, an 11th electrode, and a 12th electrode of the twelve electrodes are configured in a rotation sequence,wherein the 8-fold symmetry has four planes of symmetry, the first and the third planes of symmetry of the four planes of symmetry are perpendicular to each other, the second and the fourth planes of symmetry of the four planes of symmetry are perpendicular to each other, an angle between the first and the second planes of symmetry is 45°
, and each of said four planes contains the optical axis,wherein the first plane of symmetry bisects the inner ends of the 1st and 7th electrodes, the second plane of symmetry bisects the through slit between the 2nd and 3rd electrodes and the through slit between the 8th and 9th electrodes, the third plane of symmetry bisects the 4th and 10th electrodes, the fourth plane of symmetry bisects the through slit between the 5th and 6th electrodes and the through slit between the 11th and 12th electrodes,wherein said twelve electrodes are excited to generate an electric dipole field in a direction perpendicular to the optical axis.
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Accused Products
Abstract
This invention provides a multi-pole type Wien filter, which acts more purely approaching its fundamentally expected performance. A 12-electrode electric device acts as an electric deflector, or acts as an electric deflector and an electric stigmator together. A cylindrical 4-coil magnetic device with a magnetic core acts as a magnetic deflector. Both can produce a dipole field while only incurring a negligibly-small 3rd order field harmonic. The magnetic core enhances the strength and more preciously regulates the distribution of the magnetic field originally generated by the coils. Then two ways to construct a Wien filter are proposed. One way is based on both of the foregoing electric and magnetic devices, and the other way is based on the foregoing electric device and a conventional magnetic deflector. The astigmatism in each of such Wien filters can be compensated by the electric stigmator of the electric device.
25 Citations
26 Claims
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1. An electric device, comprising:
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twelve electrodes, inner ends of said twelve electrodes configuring a cylindrical through hole and an 8-fold symmetry, twelve through slits separating the twelve electrodes respectively and parallel to a central axis of said hole, said central axis being an optical axis of the electric device, wherein each of said twelve through slits has a central plane containing the optical axis, wherein a 1st electrode, a 2nd electrode, a 3rd electrode, a 4th electrode, a 5th electrode, a 6th electrode, a 7th electrode, an 8th electrode, a 9th electrode, a 10th electrode, an 11th electrode, and a 12th electrode of the twelve electrodes are configured in a rotation sequence, wherein the 8-fold symmetry has four planes of symmetry, the first and the third planes of symmetry of the four planes of symmetry are perpendicular to each other, the second and the fourth planes of symmetry of the four planes of symmetry are perpendicular to each other, an angle between the first and the second planes of symmetry is 45°
, and each of said four planes contains the optical axis,wherein the first plane of symmetry bisects the inner ends of the 1st and 7th electrodes, the second plane of symmetry bisects the through slit between the 2nd and 3rd electrodes and the through slit between the 8th and 9th electrodes, the third plane of symmetry bisects the 4th and 10th electrodes, the fourth plane of symmetry bisects the through slit between the 5th and 6th electrodes and the through slit between the 11th and 12th electrodes, wherein said twelve electrodes are excited to generate an electric dipole field in a direction perpendicular to the optical axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 17, 18, 19, 20, 21, 22, 23)
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10. A magnetic device, comprising:
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a cylindrical magnetic core with a cylindrical through hole, a central axis of said hole being an optical axis of said magnetic device; and four coils respectively winding around an inner and an outer sidewalls of said magnetic core and parallel to the optical axis, wherein a 1st coil, a 2nd coil, a 3rd coil, and a 4th coil of said four coils are configured in a rotation sequence, the 1st and 3rd coils are bisected by a common central plane and the 2nd and 4th coils are bisected by the other common central plane, and both of the two common central planes contain the optical axis, wherein a first and a second planes respectively bisect two adjacent angles between the two common central planes, a first and a second directions are both perpendicular to the optical axis and respectively parallel to the first and the second planes, wherein the said four coils are excited to generate a magnetic dipole filed in a direction perpendicular to the optical axis. - View Dependent Claims (11, 12, 13, 16, 26)
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24. A Wien filter, comprising:
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a cylindrical magnetic device including; a cylindrical magnetic core with a first coaxial-cylindrical through hole, a central axis of the coaxial-cylindrical through hole being an optical axis of said magnetic device and the Wien filter; and four coils respectively winding around an inner and an outer sidewalls of said magnetic core and parallel to the optical axis, said four coils configuring a 4-fold symmetry in any sectional plane perpendicular to the optical axis such that a magnetic dipole field can be generated within the magnetic device in a direction perpendicular to the optical axis; and a cylindrical electric device including twelve electrodes, said twelve electrodes configuring a cylinder with a second coaxial-cylindrical through hole and being inside the first through hole of the magnetic core of the cylindrical magnetic device, a central axis of the second coaxial-cylindrical through hole being an optical axis of the electric device and coincident with the optical axis of the Wien filter, said twelve electrodes configuring an 8-fold symmetry and being sectorial in any sectional plane perpendicular to the optical axis, twelve through slits separating said twelve electrodes respectively and parallel to the optical axis of the electric device, each of said twelve through slits having a central plane containing the optical axis of the electric device, wherein said twelve electrodes are excited to generate one electric dipole field within the electric device in a direction perpendicular to the optical axis of the Wien filter and the magnetic dipole field, wherein each of two end portions of the second coaxial-cylindrical through hole of the electric device has a conical shape coaxial with a cylindrical central portion of said hole, such that a distribution shape of the electric dipole field can match a distribution shape of the magnetic dipole field along the optical axis of the Wien filter. - View Dependent Claims (25)
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Specification