US2272353A - Electronic microscope - Google Patents

Electronic microscope Download PDF

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Publication number
US2272353A
US2272353A US353338A US35333840A US2272353A US 2272353 A US2272353 A US 2272353A US 353338 A US353338 A US 353338A US 35333840 A US35333840 A US 35333840A US 2272353 A US2272353 A US 2272353A
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United States
Prior art keywords
cathode
electron
diaphragm
pointed
source
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
US353338A
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English (en)
Inventor
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
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Fides Gesellschaft fuer die Verwaltung und Verwertung von Gewerblichen Schutzrechten mbH
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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
    • 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
    • H01J37/06—Electron sources; Electron guns
    • H01J37/073—Electron guns using field emission, photo emission, or secondary emission electron sources

Definitions

  • each point of the object is struck by an approximately needleshaped beam of rays which converges towards the center of the objective diaphragm and passes through a larger zone of the object than corresponds to the irradiated zone of the objective diaphragm.
  • the main object of the invention is to provide electron-optical apparatus, in particular electron microscopes, with a cathode which fulfills all the conditions mentioned. above.
  • the electron source of a microscopic or other electron-optical apparatus consists of a pointed or needle-shaped cold cathode formed, for instance, of a tungsten filament. Aside from the fact that such a cathode dispenses with the heat sources which are otherwise necessary, the arrangement may be so designed that an additional control electrode as well as the means for producing the control voltage are also eliminated.
  • the pointed cathode may be arranged in a support impressed with the same voltage as the cathode proper and so designed that it shields the lines of force which emerge laterally from the pointed cathode which otherwise could pass to the anode.
  • a particuilarly good shielding efifect is attained if an auxiliary electrode is employed which is impressed with a negative voltage as compared with that of the cathode.
  • a pointed cathode as an electron emitting source of electron-optical apparatus may be employed to advantage in various types of electronic microscopes.
  • the cathode may be employed in electronic microscopes in which the electron rays emitting from the cathode are converged by means of a condenser lens onto the object and after having passed through the latter are subjected to one or more electron lenses serving to project a magnified image of the object onto a luminescent screen or photographic plate.
  • the invention may also be applied to an arrangement in which the object is arranged more closely to the cathode, for instance directly in front of the cathode.
  • the beam of electron rays emitted from the pointed cathode is first concentrated by means of one or more electron optical reduction lenses to a' very fine luminous point, behind or in front of which the object to be magnified is arranged in the path of the rays.
  • a diaphragm with a very fine aperture is placed in the neighborhood of the luminous point for the production of an image with augmented contrasts.
  • Figs. 1 to 3 show three different examples of a pointed cathode according to the invention
  • Figs. 4 to 6 show three different forms of electronic microscopes.
  • l denotes a pointed cathode which is held in position by a support 2.
  • 3 denotes the anode and 4- the diaphragm through whose aperture the cathode rays pass to strike the object (not shown).
  • Fig. 1 a comparatively large number of lines of force emerge laterally from the pointed cathode and pass to the anode.
  • An arrangement in which the lines of force are more concentrated on the aperture of the diaphragm 4 is shown in Fig. 2. This effect is brought about by giving the support 6 for the pointed cathode a particular shape so that it contains the needleshaped cathode l within a cup-shaped cavity.
  • a still greater concentration of the lines of force on the diaphragm aperture 4 is obtained if a control electrode 1 according to Fig. 3 is employed and impressed with a negative potential as compared with that of the cathode l.
  • Fig. 4 is a longitudinal sectional view of an electronic microscope in which the rays pass through the object and thence through an objective lens.
  • ll denotes the pointed cold cathode of the electron emitting source. From this cathode a beam of electron rays is emitted at an aperture angle 20:5. The electron rays are converged with the aid of a condenser coil 12 and pass through the diaphragm I3 carrying the object.
  • an objective coil It provided with an objective diaphragm
  • a fluorescent screen or photographic plate for producing an intermediate image is indicated at I5.
  • a indicates the distance between the electron source and the condenser lens
  • b the distance between the condenser lens and the objective diaphragm I5
  • I the distance between the objective diaphragm and the optical plane of the image produced by the objective lens
  • a the distance of the-object from the objective diaphragm.
  • F denotes the focal length of the objective lens. If dk denotes the diameter of the cathode, do the diameter of the object field. and do ⁇ ! the diameter of the objective diaphragm, the following equations are applicable:
  • I I d 2g,a,az2%a,f
  • Fig. 5 also shows part of the vacuum vessel of the microscope formed of the vessel portions 29, 30 and 3
  • FIG. 6 A very simple electron optical magnifying device also containing a pointed cathode according to the invention is shown in Fig. 6.
  • pass directly through the object 32 which is projected on a fluorescent screen 33, or on a photographic plate which may replace the screen.
  • an electron-optical apparatus having a source of an electron beam, means for holding an object in the path of said beam, and electronoptical lens means for causing said beam to produce a magnified image of the object, said source havinga cold cathode of pointed shape directed towards the object.
  • an electron-optical apparatus having a source of an electron beam, means for holding an object in the path of said beam, and electronoptical lens means for causing said beam to produce a magnified image of the object, said source having a needle-shaped cathode, an anode diaphragm having an opening opposite the point of said cathode, and a conductive body surrounding the shaft portion of said needle-shaped cathode to shield the lines oi force emerging laterally from said cathode.
  • an electron-optical apparatus having a source of an electron beam, means for holding an object in the path of said beam, and electronoptical lens means for causing said beam to produce a magnified image of the object, said source having a cold cathode of pointed shape directed towards the object, an anode having an opening opposite the point of said cathode, and a conductive support carrying said cathode and forming a cavity surrounding said cathode to shield said anode from lines of force emerging laterally from said cathode.
  • an electron-optical apparatus having a source of an electron beam, means for holding an object in the path of said beam. and electronoptical lens means for causing said beam to produce a magnified image of the object, said source having a needle-shaped cold cathode, an anode having an opening'opposite the point of said cathode, and an electrode having a negative potential as regards said cathode and surrounding said cathode to shieldsaid anode from lines of force emerging laterally from said cathode.
  • An electron microscope comprising a source of an electron beam having a cold cathode oi pointed shape and an anode diaphragm with an opening opposite the point of said cathode, a condensing lens, an object diaphragm, an objective lens having an objective diaphragm, and a condensing lens arranged between said source and said object diaphragm and designed for concentrating said beam so as to taper through said object diaphragm to a focal point lying substantially in the plane of said objective diaphragm.
  • An electron microscope comprising a source of an electron beam having a cold cathode of pointed shape and an anode diaphragm with an opening opposite the point oi said cathode. diaphragm means for holding an object, said means being arranged immediately in front of said electron source, and electron-optical means for causing the beam to produce a. magnified image of the object.
  • An electron microscope comprising a source of an electron beam having a cold cathode of pointed shape and an anode diaphragm with an opening opposite the point 01' said cathode, electron-optical reduction lens means for concentrating the beam to form a fine beam point object-holding means arranged so as to place the object in proximity to said beam point, and means arranged behind the obect its magnified image. J for renewing ERNST RUSKA.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
US353338A 1939-07-22 1940-08-20 Electronic microscope Expired - Lifetime US2272353A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE220324X 1939-07-22

Publications (1)

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US2272353A true US2272353A (en) 1942-02-10

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US353338A Expired - Lifetime US2272353A (en) 1939-07-22 1940-08-20 Electronic microscope

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US (1) US2272353A (de)
CH (1) CH220324A (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421696A (en) * 1945-03-01 1947-06-03 Rca Corp Specimen holder assembly
US2594099A (en) * 1950-04-22 1952-04-22 Ite Circuit Breaker Ltd Focusing coil for cathode-ray tubes
US2619607A (en) * 1951-03-10 1952-11-25 Glaser Steers Corp Internal focusing device
US2771568A (en) * 1951-01-31 1956-11-20 Zeiss Carl Utilizing electron energy for physically and chemically changing members
US2886736A (en) * 1954-02-02 1959-05-12 Research Corp Current rectifier
US2897396A (en) * 1955-05-10 1959-07-28 Vakutronik Veb Electron emitting system
US3728570A (en) * 1968-07-07 1973-04-17 Department Of Eng University O Electron probe forming system
US3866077A (en) * 1971-07-09 1975-02-11 Nat Res Dev Electron emitters
US4672553A (en) * 1983-02-03 1987-06-09 Goody Products, Inc. Order processing method and apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846660A (en) * 1969-08-06 1974-11-05 Gen Electric Electron beam generating system with collimated focusing means

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2421696A (en) * 1945-03-01 1947-06-03 Rca Corp Specimen holder assembly
US2594099A (en) * 1950-04-22 1952-04-22 Ite Circuit Breaker Ltd Focusing coil for cathode-ray tubes
US2771568A (en) * 1951-01-31 1956-11-20 Zeiss Carl Utilizing electron energy for physically and chemically changing members
US2619607A (en) * 1951-03-10 1952-11-25 Glaser Steers Corp Internal focusing device
US2886736A (en) * 1954-02-02 1959-05-12 Research Corp Current rectifier
US2897396A (en) * 1955-05-10 1959-07-28 Vakutronik Veb Electron emitting system
US3728570A (en) * 1968-07-07 1973-04-17 Department Of Eng University O Electron probe forming system
US3866077A (en) * 1971-07-09 1975-02-11 Nat Res Dev Electron emitters
US4672553A (en) * 1983-02-03 1987-06-09 Goody Products, Inc. Order processing method and apparatus

Also Published As

Publication number Publication date
CH220324A (de) 1942-03-31

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