US3597608A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for adjusting electron beam in electron microscope
Assignee: Carl Zeiss AG
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Filing: 1969-02-14
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Granted: 1971-08-03
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Expires: 1989-02-14
Abstract
Abstract In an electron beam microscope wherein the beam is laterally adjusted to a desired position, in which it visibly impinges on an image screen, by adjusting the intensity and polarity of the unidirectional magnetic field of each of several electromagnetic deflecting units arranged at different sides of the beam, adjustment of the beam is facilitated by temporarily generating alternating magnetic fields in all but one of said units for laterally wobbling the beam while adjusting the unidirectional magnetic field of the latter unit so that the wobbling beam periodically momentarily assumes its aforesaid adjusted position. Thereafter, alternating magnetic fields are generated in all but one of the remaining unadjusted units which are successively adjusted by means of their unidirectional magnetic fields in the above manner until all but one of the units is adjusted. The unidirectional magnetic field of the latter unit is then adjusted to complete the adjustment of the position of the beam.
Inventors
- 👤 Ernst Gutter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:16
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/147; H01J37/1471
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
181 words
In an electron microscope having a relatively small effective illuminating aperture, the method of adjusting the electron beam to a desired image position using plural independent beampositioning deflection systems on at least two different deflection axes, each of said deflection systems being normally excited with direct-current energy at an independently adjusted magnitude less than the excitation capacity of the deflection system, said method comprising: first, temporarily wobbling the beam by exciting all but one of the deflection systems with alternating-current energy at peak intensities exceeding said magnitude, at least one of said deflection systems being energized with an excitation frequency differing from that apPlied to others of said deflection systems to define a beat frequency therebetween, while adjusting the level of directcurrent energy to said one deflection system until the beam is periodically aligned with the effective aperture; thereafter repeating the beam-wobbling and adjusting cycle as to remaining unadjusted deflection systems until all but one deflection system is adjusted; and then adjusting the level of direct-current energy to said last-mentioned one deflection system until the beam passes through the effective aperture.
Claim 2
Dependent Claim
181 words
In an electron microscope having a relatively small effective illuminating aperture, the method of adjusting the electron beam to a desired image position using plural independent beampositioning deflection systems on at least two different deflection axes, each of said deflection systems being normally excited with direct-current energy at an independently adjusted magnitude less than the excitation capacity of the deflection system, said method comprising: first, temporarily wobbling the beam by exciting all but one of the deflection systems with alternating-current energy at peak intensities exceeding said magnitude, at least one of said deflection systems being energized with an excitation frequency differing from that apPlied to others of said deflection systems to define a beat frequency therebetween, while adjusting the level of directcurrent energy to said one deflection system until the beam is periodically aligned with the effective aperture; thereafter repeating the beam-wobbling and adjusting cycle as to remaining unadjusted deflection systems until all but one deflection system is adjusted; and then adjusting the level of direct-current energy to said last-mentioned one deflection system until the beam passes through the effective aperture.
Claim 3
Dependent Claim
35 words
The method of claim 1, in which the number of deflection systems is four, and in which the beam-wobbling and deflection-adjusting cycle is repeated three times to accomplish adjustment of the first three deflection systems.
Claim 4
Dependent Claim
27 words
The method of claim 1 in which the frequencies of the respective alternating fields are sufficiently different to provide a beat frequency of more than 5 cycles.
Claim 5
Dependent Claim
57 words
The method of claim 1 for adjusting an electron microscope having four beam-positioning electromagnetic deflecting systems, wherein alternating-current energy is temporarily supplied to three of said systems; as to which three systems, two are excited at the same frequency but at different intensities and polarities, and the third is excited with alternating-current energy at a different frequency.
Claim 6
Dependent Claim
159 words
An electron beam aligning system for an electron microscope comprising an electron gun for generating an electron beam, plural independent deflection systems for selectively positioning said beam about associated directions in a beam image plane, each of said deflection systems including means for displacing said beam about said associated direction in an amount dependent upon the amplitude of the excitation applied thereto, beam-adjusting control means having separate output connections for energizing said deflection systems, said control means including independently variable means for selectively supplying direct current to an associated one of said deflection systems for fixedly displaying said beam, alternating current supplying means for selectively supplying alternating current, of a peak value sufficient to overcome electron beam misalignment, of at least two different frequencies having a beat frequency therebetween to said deflection systems for variably displacing said beam, and switch means for selectively connecting said deflection systems with said direct current supplying means and said alternating current supplying means.
Claim 7
Dependent Claim
159 words
An electron beam aligning system for an electron microscope comprising an electron gun for generating an electron beam, plural independent deflection systems for selectively positioning said beam about associated directions in a beam image plane, each of said deflection systems including means for displacing said beam about said associated direction in an amount dependent upon the amplitude of the excitation applied thereto, beam-adjusting control means having separate output connections for energizing said deflection systems, said control means including independently variable means for selectively supplying direct current to an associated one of said deflection systems for fixedly displaying said beam, alternating current supplying means for selectively supplying alternating current, of a peak value sufficient to overcome electron beam misalignment, of at least two different frequencies having a beat frequency therebetween to said deflection systems for variably displacing said beam, and switch means for selectively connecting said deflection systems with said direct current supplying means and said alternating current supplying means.
Claim 8
Dependent Claim
60 words
The apparatus of claim 5 in which said alternating-current supply means are adapted to supply alternating current at least at two different frequencies and in which said switch means are adapted for connecting one deflection system for excitation at one of said frequencies and for connecting at least one of the other deflection systems for excitation at a different frequency.
Claim 9
Dependent Claim
24 words
The apparatus of claim 6 in which the differences in said frequencies are sufficient to provide a beat frequency of at least 5 cycles.
Claim 10
Dependent Claim
26 words
The apparatus of claim 5, in which said alternating current supply means are adapted to supply alternating current at different frequencies to all last-mentioned deflection systems.
Claim 11
Dependent Claim
36 words
The apparatus of claim 5, in which said control means is adapted for supply by a direct-current source and in which said alternating-current supply means includes generators of different alternating-current frequencies operated by the direct-current source.
Claim 12
Dependent Claim
14 words
The apparatus of claim 5, in which the number of deflection systems is four.
Claim 13
Dependent Claim
42 words
The apparatus of claim 10, in which two of said deflection systems are positioned for beam deflection on a first axis and the other two deflection systems are positioned for beam deflection on a second axis, orthogonally related to said first axis.
Claim 14
Dependent Claim
143 words
The apparatus of claim 10, in which said switch means is a single switch having plural positions, said switch in a first position connecting a first of said deflection systems to its selectIvely variable direct-current supply while connecting the other three deflection systems to their respective alternating-current supply means, said switch in a second position connecting said first and a second of said deflection systems to their respective selectively variable direct-current supplies while connecting the other two deflection systems to their respective alternating-current supply means, said switch in a third position connecting said first and second and a third of said deflection systems to their respective selectively variable direct-current supplies while connecting the last one of said deflection systems to its alternating-current supply means, and said switch in a fourth position connecting all said deflection systems to their respective selectively variable direct-current supplies.
Claim 15
Dependent Claim
22 words
The apparatus of claim 12, in which said respective alternating-current supply means provide at least two different frequencies to said deflection systems.
Claim 16
Dependent Claim
71 words
The apparatus of claim 13, in which said microscope includes beam-collecting means at substantially the image plane and having an electrical output responsive to electron-beam impingement thereon, and automatic means responsive to an output generated by said beam-collecting means, said automatic means including actuating means connected to step said switch progressively, from its first to the next of its succeeding positions, upon each newly generated output response of said beam-collecting means.
References Cited (Backward Citations)
US2626358A
Cited
US2856534A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |