US2209669A - Magnetic lens for electron microscopes - Google Patents

Magnetic lens for electron microscopes Download PDF

Info

Publication number
US2209669A
US2209669A US223458A US22345838A US2209669A US 2209669 A US2209669 A US 2209669A US 223458 A US223458 A US 223458A US 22345838 A US22345838 A US 22345838A US 2209669 A US2209669 A US 2209669A
Authority
US
United States
Prior art keywords
pole
magnetic lens
electron microscopes
cone
core
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US223458A
Other languages
English (en)
Inventor
Borries Bodo Von
Ruska Ernst
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.)
Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
Original Assignee
Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH filed Critical Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
Application granted granted Critical
Publication of US2209669A publication Critical patent/US2209669A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01J37/10—Lenses
    • H01J37/14—Lenses magnetic
    • H01J37/141—Electromagnetic lenses

Definitions

  • the invention relates to a magnetic lens such as may, for instance, be employed in electron microscopes of the type disclosed for instance in our copending application, Serial No. 225,278.
  • magnet pole systems To attain small focal lengths necessary for this type of microscope, magnet pole systems must be used in such lenses whose pole pieces are so arranged as to be spaced from one another about 1 mm. or less. In the case of a symmetrical design of the pole pieces the object can therefore hardly be placed excessively close to the magnetic lens. Consequently, it has been proposed to use asymmetric pole pieces in suchv a manner that one pole piece represents a rather obtuse-angled cone and the other pole piece a rather acute-angled cone. Thus it becomes possible to place the object at the side of the obtuse-angled pole piece suificiently close to the lens.
  • an asymmetric magnet pole system of the above-described character is designed so that the magnetic saturation occurs at least at the ends of both pole pieces practically at the same time.
  • Figs. 1 and 2 represent semi-diagrammatically central sectional elevations of two forms in which so as examples the invention may be reduced to practice.
  • i denotes the magnet coil surrounded by the circular steel jacket 2.
  • the pole pieces have the form of cones whose vertexes are pro- 35 vided with a central axially directed aperture.
  • the apertured pole piece 3 facing the object has the form of an inverted obtuse-angled cone, whereas the angle of the apertured pole piece i is smaller, acute in the present case.
  • the cross- 40 section of the pole pieces is chosen in such a manner that the magnetic saturation occurs at the ends of both pole pieces practically at the same time. To this end it is necessary to give the pole piece t a larger cross-section than the pole piece 3 in view of the leakage flux.
  • both pole pieces extend outwardly.
  • the arrangement may be modified so 50 that the convex side of the pole piece 3 faces the object as shown schematically in Fig. 2.
  • the cross-section of the pole pieces may be so dimensioned that the saturation occurs at the same time at the ends of both 55 pole pieces.
  • a magnetic lens having an asymmetric pole system, and energizing means for developing a magnetic flux in said pole system, said system comprising an annular magnet core having in- 5 wardly extending cone-shaped pole shoes provided at its ends, the apexes of said cones being closely adjacent to one another and the cone angle of one pole shoe being relatively large and that of the other pole shoe being relatively small, 10 so that the apex portions of said cones both become located closely adjacent to one end of said annular core, the cross section of said pole shoes being dimensioned relatively to the flux density so that at least the ends of both pole shoes be- 15 come saturated at the same time and at the same flux density when the core is energized.
  • a magnetic lens having an asymmetric pole system, and energizing means for developing a magnetic flux in said pole system
  • said system 20 comprising an annular magnet core having inwardly extending cone-shaped pole shoes provided at its ends, the apexes of said cones being closely adjacent to one another and the cone angle of one pole shoe being relatively large and 25 that of the other pole shoe being relatively small, so that the apex portions of said cones both become located closely adjacent to one end of said annular core, the cross section of said pole shoes being dimensioned relatively to the flux density so that at least the ends of both pole shoes become saturated at the same time and at the same flux density when the core is energized, and a perforation in each pole shoe apex located in the common central axis of the shoes.
  • a magnetic lens having an asymmetric pole system and energizing means for developing a magnetic flux in said pole system, said system comprising an annular magnet core having inwardly extending cone-shaped pole shoes provided at its ends, the angles of said cones opposing one another and their apexes being closely adjacent to one another, the cone of one pole shoe including a relatively large obtuse angle and the cone of the other pole shoe including a relatively small acut angle, so that the apex portions of both cones become located closely adjacent to one end of said annular core, the cross section of said pole shoes being dimensioned relatively to the flux density so that at least the ends of both pole shoes become saturated at the same time and at the same flux density when the core is energized.
  • a magnetic lens having an asymmetric pole system, and energizing means for developing a pole shoe including a relatively large obtuse an-j gle, and the cone of the other pole shoe including a relatively small acute angle, so that the.
  • both cones become located closely adjacent to one end of said annular core, the cross section of said pole shoes being dimensioned relatively to the flux density so that at least the ends, of both pole shoes become saturated at the same time and at the same flux density when the core is energized.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Beam Exposure (AREA)
  • Eyeglasses (AREA)
US223458A 1937-08-16 1938-08-06 Magnetic lens for electron microscopes Expired - Lifetime US2209669A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE517680X 1937-08-16

Publications (1)

Publication Number Publication Date
US2209669A true US2209669A (en) 1940-07-30

Family

ID=6549644

Family Applications (1)

Application Number Title Priority Date Filing Date
US223458A Expired - Lifetime US2209669A (en) 1937-08-16 1938-08-06 Magnetic lens for electron microscopes

Country Status (4)

Country Link
US (1) US2209669A (enrdf_load_stackoverflow)
BE (1) BE429637A (enrdf_load_stackoverflow)
FR (1) FR841823A (enrdf_load_stackoverflow)
GB (1) GB517680A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2418432A (en) * 1944-05-01 1947-04-01 Rca Corp Magnetic electron lens system
US2648036A (en) * 1946-03-12 1953-08-04 Us Navy Adjustable focusing coil
US3509503A (en) * 1967-02-27 1970-04-28 Nippon Electron Optics Lab Objective lens pole pieces
US4541890A (en) * 1982-06-01 1985-09-17 International Business Machines Corporation Hall ion generator for working surfaces with a low energy high intensity ion beam

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE759837C (de) * 1940-05-07 1954-06-28 Manfred Von Ardenne Magnetische Linse fuer Elektronenmikroskope mit einem unsymmetrisch zur Spulenmitte liegenden Polschuhsystem

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2418432A (en) * 1944-05-01 1947-04-01 Rca Corp Magnetic electron lens system
US2648036A (en) * 1946-03-12 1953-08-04 Us Navy Adjustable focusing coil
US3509503A (en) * 1967-02-27 1970-04-28 Nippon Electron Optics Lab Objective lens pole pieces
US4541890A (en) * 1982-06-01 1985-09-17 International Business Machines Corporation Hall ion generator for working surfaces with a low energy high intensity ion beam

Also Published As

Publication number Publication date
BE429637A (enrdf_load_stackoverflow)
GB517680A (en) 1940-02-06
FR841823A (fr) 1939-05-31

Similar Documents

Publication Publication Date Title
US2200039A (en) Permanent magnet device for producing axially symmetrical magnetic fields
DE973258C (de) Magnetische Polschuhlinse kleiner Brennweite fuer elektronenoptische Vergroesserungen in Elektronenmikroskopen
US2209669A (en) Magnetic lens for electron microscopes
US2446855A (en) Double-acting solenoid
US2236498A (en) Deflecting yoke
GB545414A (en) Electron beam deflecting yoke
US2227711A (en) Deflecting device for cathode ray tubes
US1667766A (en) Magnetic chuck
US3585546A (en) Objective lens pole pieces
US1987555A (en) Solenoid construction
US2153643A (en) Cathode ray deflection apparatus
ES322522A1 (es) Un dispositivo de yugo electromagnetico para desviar el haz de electrones de un tubo de rayos catodicos en dos direcciones ortogonales.
US2164931A (en) Cathode ray tube deflecting device
US3150256A (en) Column for electron microscopes
US2304553A (en) Solenoid
FR852158A (fr) Objectif magnétique à courte distance focale pour microscopes électroniques
DE707331C (de) Magnetische Linse mit unsymmetrischem Polsystem
US2670450A (en) Electron microscope
DE901325C (de) Magnetostatische Polschuhlinse
SU77460A3 (ru) Электронно-лучева высокочастотна лампа
DE761193C (de) Torische Linse fuer elektrische Korpuskularstrahlen
DE1514259B2 (de) Vorrichtungen zum Abschirmen des Elektronenstrahlbündels gegen asymmetrische, magnetische Streufelder in Elektronenstrahlgeräten
GB597469A (en) Improvements in or relating to cathode-ray tubes
DE907330C (de) Linsensystem fuer Korpuskularstrahlapparate
DE2059781B2 (de) Magnetische Linsenanordnung