US2754443A - Astigmatically corrected electronic lenses - Google Patents

Astigmatically corrected electronic lenses Download PDF

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Publication number
US2754443A
US2754443A US480583A US48058355A US2754443A US 2754443 A US2754443 A US 2754443A US 480583 A US480583 A US 480583A US 48058355 A US48058355 A US 48058355A US 2754443 A US2754443 A US 2754443A
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United States
Prior art keywords
lens
corrective
ring
annular
field
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Expired - Lifetime
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US480583A
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English (en)
Inventor
Asmus Alexander
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens and Halske AG
Siemens Corp
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Siemens Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/153—Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators

Definitions

  • My invention relates to electronic lenses, for instance as used in electron microscopes, and is directed particularly to a compensating device for correcting axial astigmatism in such lenses.
  • Another object is to provide an electron lens with astigmatic correction means that can readily be adjusted from the outside of an electron microscope or other electron-optical apparatus of which the lens forms a component.
  • 1 dispose around the electron-optical axis and around the field of the lens an annular corrective body for producing an elliptic field distortion adjustable as to magnitude and direction.
  • the corrective annular body is disposed so as to surround the field-terminal system, i. e. the pole shoe or electrode systems, of the lens and is displaceable in the axial direction and also rotationally adjustable about the lens axis. This makes it possible to correct astigmatism with the aid of only two continuously variable adjustments, namely axial displacement and rotation of the corrective member. Since the corrective member surrounds the major lens parts, namely the pole shoe system or the lens electrodes, depending upon whether the lens is magnetic or electric, the desired lens correction is effected without necessity of having any structural part enter into the lens field proper.
  • the corrective member can be made of non-conducting material and be provided at suitable places with conducting metallic parts producing the desired field distortion.
  • the compensating device preferably has its ring-shaped corrective member provided with two control shafts operable from the outside of the evacuated envelope. of the electron-optical apparatus, one shaft serving for rotational adjustment and the other for adjusting axial displacement of the member.
  • the corrective member to be axially and rotationally adjustable, is mounted with the aid of two rings.
  • One of these mounting rings has gear teeth meshing with a pinion for rotational adjustment.
  • the other ring has a screw thread which engages a threaded rotatable part and performs an axial displacement when the part is turned by another pinion.
  • a corrective iron member of suitable asymmetry between two brass rings, one having an outer, annular row of gear teeth in mesh with a pinion for rotational adjustment of the member, while the other ring is externally threaded and engaged by a rotatable, internally-threaded sleeve which in turn is rotatable by means of another pinion for thus imparting axial displacement to the corrective member.
  • one of the pole shoes of the lens to be corrected serves as a gliding surface for the corrective member.
  • Fig. 1 illustrates a vertical, partially cross-sectional view of a magnetic electron lens according to the invention
  • Fig. 2 is a perspective view of the ring-shaped corrective member
  • Fig. 3 shows the lower ring for turning the corrective member to control the radial angle at which distortion is introduced
  • Fig. 4 illustrates an alternative embodiment of the invention.
  • an upper pole shoe 1 and a lower pole shoe 2 form the field-terminal structures of the lens.
  • the magnetic circuit of the lens comprises two annular cover plates 3 and 4, an outer cylindrical jacket 5, and an inner cylindrical tube 6.
  • An excitation winding 7 is disposed in the interior of the magnetic shield or capsule thus formed and is upwardly confined by an annular disc 8 of brass.
  • a corrective member 9 serves to correct the elliptical astigmatism of the lens. At two diametrically opposite places, the member 9 is given suitable asymmetries capable of introducing a greater or lesser elliptical distortion of the field, depending upon the positioning of the member.
  • the ring-shaped corrective member 9 has two diametrically opposed iron lugs 10 and 11 serving as the zones of asymmetry.
  • the ring-shaped corrective member 9 itself may also consist of magnetic material but may also be made of brass.
  • Member 9 is mounted between two brass rings 12 and '13; and the entire subassembly of parts 9,. 12 and 13 is so shaped and dimensioned that the outer surface of the lower pole shoe 2 'serves .as 'a gliding surface for that subassembly.
  • Two control shafts 14 and 15 serve for adjustment of the ring-shaped corrective member 9.
  • the shafts are coaxial and extend, one within the other, through the wall of the vacuum jacket 5.
  • the central control shaft 14 carries on its inner end a driving pinion meshing with an annular toothed portion 17 of ring 13.
  • This drive mecha nism serves for adjusting the ring-shaped corrective member. 9 to rotate the corrective field distortion.-
  • the two' iron lugs and 11, fixed with respect to the corrective member 9, project into complementary upper slots 18 and 19 in an upwardly extending collar 20 forming partjof ring 13, whereby the corrective member is rotated the sleeve 23, the ring 12 is prevented from turning by V a pin 24 which is securely fixed at one end to the upper Wall.
  • the two control shafts 14 and 15 may extend .to the outside through releasable and non-interchangeable clutch means.
  • the'control knobs 27. and 28 of the two shafts should have fixed angular positions relative to the respective shafts so that the knobs may serve as position-indicating means. 7 a
  • Fig. 4 illustrates schematically another embodiment of a corrective device for a magnetic lens. Only the essential parts of the pole shoe system of the lens itself are shown.
  • the pole shoe system comprises an upper pole shoe 3!, a lower pole shoe 32, and a non-magnetic intermediate member 33 rigidly securing the pole shoes to each other.
  • a ring-shaped corrective member 34 surrounding the pole shoe system is provided for compensating axial astigmatism in the lens.
  • the compensating member is made of brass and has a lower annular flange 35. The necessary asymmetry is provided by diametrically opposed iron lugs 36 and 37 incorporated in the ring.
  • the corrective member 34 is cooperatively connected with a control shaft 37 carrying at its inner'end a driving 7 pinion 38 meshing with an annular toothed portion of a brass ring 39.
  • the brass lug 41 upon turning, carries with it the ring-shaped corrective member 34 and turns it about the pole shoe system for changing the direction of field distortion.
  • the lens system comprises a control shaft 43 which carries on its inner end a driving pinion 44 meshing with an annular toothed portion 45 of a positioning ring 46.
  • The'turning movement of this positioning ring is imparted to a ring member 49 through two downwardly-extending pins 47, 48 each fixed at one end in positioning ring 46 and fitting slidably at their other ends in complementary openings in the ring member 49;
  • the ring member 49 has an' inner annular groove 5% within which the peripheral edge of a flange portion of the ring-shaped corrective member 34 is seated.
  • the ring member 49 has an external screw thread 51 screwed within an internally-threaded fixed member 52, whereby, when turning the ring member 46, the ring member 49 will be screwed upwardly or downwardly in the internally-threaded member 52. Axial movement is thereby imparted to the corrective member 34 thus varying the strength of field distortion. By suitable proportioning of the frictional conditions, the corrective member 34 is prevented from being carried along by the turning motion of the ring member 4?.
  • the outer control knobs 53 and 54 in this embodiment of the invention are fixed to the ends of the respective control shafts 37 and 43, which extend through the vacuum wall (not shown in Fig. 6) to be outside of the apparatus.
  • An electron-optical lens comprising annular lensfield terminal structures fixed and coaxially spaced relative to each other and defining a lens field and a lens axis, a corrective body of annular shape surrounding said structure, said corrective body being asymmetrically designedat diametrically opposed locations for elliptically distorting the lens field, said annular body being axially displaceable relative to said structure and being rotatably adjustable about the lens axis for compensating .axial astigmatism.
  • An electron-optical lens comprising two annular magnet pole shoes fixed and coaxially spaced fromeach other to form a lens-field gap defining a lens axis, a corrective body of annular shape having a larger inner diameter than said pole shoes and surrounding said gap, said corrective body being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, said annular body being axially displaceable relative to said structure and being rotatably adjustable about the lens axis for compensating axial astigmatism.
  • An electronic lens comprising a vacuum envelope, annular lens-field terminal structures within said envelope coaxially spaced from each other and defining a lens field and a lens axis, an annular corrective memberdisposed in said envelope and surrounding said axis, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, and manually-controllable drive means'for independently varying the axial and rotary positions of said corrective 'member with respect to said axis, said drive means extending from within to the outside of said envelope.
  • An electronic lens comprising annular lens-field terminal structures coaxially spaced relative each other and defining a lens' field and lens axis, an annular corrective member surrounding said axis, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, a first drive mechanism for controlling the axial position of said corrective member along saidaxis, and a second drive mechanism for controlling the rotary position of said corrective member with'respect to said axis.
  • An electronic lens comprising a vacuum envelope, annular lens-field terminal structures coaxially spaced from each other within said envelope and defining a lens field and a lens axis, an annular corrective member disposed in said envelope surrounding said axis, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, a first drive mechanism for controlling the axial position of said corrective member along said axis, and a second drive mechanism for controlling the rotaryposition of said corrective member with respect to said axis,
  • said first and second drive mechanisms being disposed within said envelope and comprising a pair of manually operable drive shafts, one of said shafts being tubular and having the other of said shafts coaxially disposed therein, and said two shafts extending from Within to the outside of said envelope.
  • An electronic lens comprising annular lens-field terminal structures coaxially spaced relative each other and defining a lens field and a lens axis, an annular corrective member surrounding said axis, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, an externally-threaded ring member coaxial With said corrective member and rotatable with respect thereto, a rotatable internally-threaded member Within which said externally-threaded member is threaded, said internally-threaded member having a first annular gear portion, a first drive gear in mesh with said first annular gear portion for turning said internally threaded member, a second ring member coaxial with said corrective member, means interconnecting said second ring member and said corrective member for simultaneous cooperative rotary motion, said second ring member having a second annular gear portion, and a second drive gear in mesh with said second annular gear portion for turning said second ring member.
  • An electronic lens comprising two fixed magnet pole shoes coaxially spaced from each other to form a lensfield gap defining a lens axis, a corrective member of annular shape having a larger inner diameter than the outer diameter of said pole shoes and surrounding said gap, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, a first drive mechanism for controlling the axial position of said corrective member along said axis, and a second drive mechanism for controlling the rotary position of said corrective member With respect to said axis.
  • An electronic lens comprising two fixed magnet pole shoes coaxially spaced from each other to form a lensfield gap defining a lens axis, one of said pole shoes having an annular outer slide surface, a corrective member of annular shape having a larger inner diameter than the outer diameter of said pole shoes and surrounding said gap, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, holding means seated upon said slide surface and connected with said corrective member whereby said member is rotatable and axially displaceable relative to said slide surface, a first drive mechanism engaging said holding means for controlling the axial position of said corrective member along said axis, and a second drive mechanism engaging said holding means for controlling the rotary position of said corrective member with respect to said axis.
  • An electronic lens comprising two fixed magnet pole shoes coaxially spaced from each other to form a lensfield gap defining a lens axis, a. corrective member of annular shape having a larger inner diameter than the outer diameter of said pole shoes and surrounding said gap, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, an externally-threaded ring member coaxial with said corrective member and rotatable with respect thereto, a rotatable internally-threaded member within which said externally-threaded member is threaded, said internally-threaded member having a first annular gear portion for turning said internally theaded tember, a second ring member coaxial with said corrective member, means interconnecting said second ring member and said corrective member for simultaneous cooperative rotary motion, said second ring member having a second annular gear portion, and a second drive gear in mesh with said second annular gear portion for turning said second ring member.
  • An electronic lens comprising two fixed magnet pole shoes coaxially spaced from each other to form a lens-field gap defining a lens axis, a corrective member of annular shape having a larger inner diameter than the outer diameter of said pole shoes and surrounding said gap, said corrective member being asymmetrically designed at diametrically opposed locations for elliptically distorting the lens field, an externally-threaded annular member coaxial with said corrective member and rotatable with respect thereto, means interconnecting said externally-threaded member and said corrective member for simultaneous axial motion, a fixed, internally-threaded member within which said externally-threaded member is threadedly engaged, a first ring member coaxial with said corrective member and having a first annular gear portion, relative axially slidable means interconnecting said first ring member and said externallythreaded member for simultaneous rotary motion, a first manually-operable drive gear in mesh with said first annular gear portion for turning said first ring member,

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Lens Barrels (AREA)
  • Electron Sources, Ion Sources (AREA)
US480583A 1954-01-22 1955-01-07 Astigmatically corrected electronic lenses Expired - Lifetime US2754443A (en)

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DE773240X 1954-01-22

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GB (1) GB773240A (enrdf_load_stackoverflow)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2910603A (en) * 1955-10-04 1959-10-27 Philips Corp Device for compensating astigmatism in a magnetic electron lens
US3071707A (en) * 1958-09-06 1963-01-01 Zeiss Carl Source of beams for producing a high intensity charge carrier beam
US3253144A (en) * 1963-05-27 1966-05-24 Tektronix Inc Electron lens having means for correcting astigmatism
CN102479651A (zh) * 2010-11-30 2012-05-30 中国科学院大连化学物理研究所 一种用于深紫外激光器与光发射电子显微镜连接的连接杆
CN105047510A (zh) * 2015-06-30 2015-11-11 北京中科科仪股份有限公司 深紫外激光器与光发射电子显微镜的对接系统
WO2021170762A1 (en) 2020-02-25 2021-09-02 The Provost, Fellows, Scholars And Other Members Of Board Of Trinity College Dublin Pole piece for a transmission electron microscope

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2219193A (en) * 1937-05-01 1940-10-22 Gen Electric Cathode ray apparatus
US2416687A (en) * 1944-03-30 1947-03-04 Bell Telephone Labor Inc Magnetic focussing device
US2587942A (en) * 1949-12-27 1952-03-04 Leitz Ernst Gmbh Electronic optical correction mechanism for magnetic lenses
US2637000A (en) * 1951-02-15 1953-04-28 Magnetic electron -lens
US2679018A (en) * 1950-06-30 1954-05-18 Rca Corp Magnetic electron lens pole piece
US2714678A (en) * 1950-09-03 1955-08-02 Siemens Ag Electron microscopes

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2219193A (en) * 1937-05-01 1940-10-22 Gen Electric Cathode ray apparatus
US2416687A (en) * 1944-03-30 1947-03-04 Bell Telephone Labor Inc Magnetic focussing device
US2587942A (en) * 1949-12-27 1952-03-04 Leitz Ernst Gmbh Electronic optical correction mechanism for magnetic lenses
US2679018A (en) * 1950-06-30 1954-05-18 Rca Corp Magnetic electron lens pole piece
US2714678A (en) * 1950-09-03 1955-08-02 Siemens Ag Electron microscopes
US2637000A (en) * 1951-02-15 1953-04-28 Magnetic electron -lens

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2910603A (en) * 1955-10-04 1959-10-27 Philips Corp Device for compensating astigmatism in a magnetic electron lens
US3071707A (en) * 1958-09-06 1963-01-01 Zeiss Carl Source of beams for producing a high intensity charge carrier beam
US3253144A (en) * 1963-05-27 1966-05-24 Tektronix Inc Electron lens having means for correcting astigmatism
CN102479651A (zh) * 2010-11-30 2012-05-30 中国科学院大连化学物理研究所 一种用于深紫外激光器与光发射电子显微镜连接的连接杆
CN102479651B (zh) * 2010-11-30 2014-05-28 中国科学院大连化学物理研究所 一种用于深紫外激光器与光发射电子显微镜连接的连接杆
CN105047510A (zh) * 2015-06-30 2015-11-11 北京中科科仪股份有限公司 深紫外激光器与光发射电子显微镜的对接系统
CN105047510B (zh) * 2015-06-30 2017-03-22 北京中科科仪股份有限公司 深紫外激光器与光发射电子显微镜的对接系统
WO2021170762A1 (en) 2020-02-25 2021-09-02 The Provost, Fellows, Scholars And Other Members Of Board Of Trinity College Dublin Pole piece for a transmission electron microscope

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GB773240A (en) 1957-04-24
NL194113A (enrdf_load_stackoverflow)

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