US2452893A - Electron lens assembly - Google Patents

Electron lens assembly Download PDF

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Publication number
US2452893A
US2452893A US673218A US67321846A US2452893A US 2452893 A US2452893 A US 2452893A US 673218 A US673218 A US 673218A US 67321846 A US67321846 A US 67321846A US 2452893 A US2452893 A US 2452893A
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US
United States
Prior art keywords
electrodes
cylinder
assembly
insulators
lens
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
US673218A
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English (en)
Inventor
Charles H Bachman
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.)
General Electric Co
Original Assignee
General Electric Co
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
Priority to FR957324D priority Critical patent/FR957324A/fr
Priority to BE480180D priority patent/BE480180A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US673218A priority patent/US2452893A/en
Application granted granted Critical
Publication of US2452893A publication Critical patent/US2452893A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/487—Replacing parts of the gun; Relative adjustment of the electrodes
    • 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
    • H01J37/12—Lenses electrostatic

Definitions

  • the lens be of such geometry that it 'gives both greatest possible electrical safety and yet is easy to assemble and assures accurate alignment. Furthermore, in order that the aberrations of the lens be a minimum, it is essential that the apertures of the various electrode ele ments be centered on the optical axis and that the electrodes themselves be accurately parallel. Accordingly, it is another object of my invention to provide a new and improved electron'lens system in which centering of the apertures of the various electrodes is obtained with accuracy and facility.
  • 'It is still another object of my invention to provide a new and improved electron lens assembly in which the leakage path through the supporting insulators for the various electrodes is considerably greater than the physical spacing of the electrodes.
  • One of the features of my invention is the use of a plurality of cylindrical insulators to support and space the electrodes of an electron lens assembly.
  • the individual insulators need be accurate in one dimension only.
  • the assembly provides both axial alignment of the electrodes and centering of all the electrodes along the optical axis of the assembly.
  • FIG. 1 is a vertical sectional view of an insulator suitably embodying the invention
  • Fig. 2 is a cross-section of the assembly of Fig. l taken along the line 2 2
  • Fig. 3 is a vertical sectional view of a modification of the assembly of Fig. 1
  • Fig. 4 is a cross-sectional View of the assembly of Fig. 3 taken along the line 4 4.
  • an electron lens assembly which comprises 2 a metallic outer cylinder l which is provided with an accurately machined inner bore and a plu rality of disk-like electrodes 2 11 which are fitted within the cylinder I.
  • the outer electrodes 2, vd may project inwardly toward the center electrode 3 a distance suilicient to provide desired spacing between the electrodes so that a desired lens effect is obtained.
  • the electrodes 2 4 are provided with respective center apertures 5 1, the central aperture 6 in the intermediate electrode being larger than ythe apertures 5, 1.
  • the electrodes 2 4 may be formed of any suitable conducting material, for example chrome-plated brass, and for the purposes to vbe pointed out later have accurately machined outer surfaces. In this fashion, the electrodes 2, 4 fit smoothly on the inner surface of the cylinder I.
  • I provide three cylindrical insulators 8 I I). While the insulators B Il) may be formed of any suitable material, such as porcelain, steatite, or Mycalex, I have found glass of the type known as Pyrex to be especially suitable in an electron lens assembly.
  • the insulator 8 is ground or prepared on itsV outer surface to fit smoothly within the cylinder l-and is provided with a centrally located raised portion I I which is carefully prepared with an inner surface f2 which is concentric with the outer surface of the insulator 8.
  • the electrode 3 is arranged to fit on the surface i2 so that theaperture 6 is held in accurate axial alignment within the cylinder I.
  • the insulating spacers 9, I0 are carefully prepared with their ends parallel and with accurately measured lengths.
  • the length of the insulators 9, I!) plus the thickness of the electrode 3 is greater than the length lof the insulator 8.
  • Such dimensioning and proportion of thickness of insulator S and of the length of insulators S, Il) provides for ease in assembly of the lens and accuracy in alignment,
  • the cylindrical sleeve l5 provides means for holding the various elements of the assembly in fixed position.
  • a stop shown as the head of a screw I4 threaded into the wall ot cylinder I.
  • the cylindrical sleeve l5 provides means for holding the various elements of the assembly in fixed position.
  • pressure is transmitted through the insulators 9, Ill and the electrodes 3', 4 against the retaining ring I3.
  • the electrodes 2, 4 are maintained at the potential of cylinder I, being in conductive contact with that cylinder.
  • Operating potential for the electrode 3 is supplied thereto by a longitudinally extending conductor I6 which is connected to the electrode 3 andA passes through an aperture (not shown) in the outer electrode 4.
  • the insulators 9, lil, and I I provide a relatively long leakage path b etween the outer electrodes and the center electrodes 3.
  • the outer electrodes have centrally positioned symmetrically Icup-shaped portions which are directed inwardly toward the center ⁇ electrode to ⁇ effect a configurationof the electric iieldin the vicinity ⁇ of, the, apertures Y5 1 to ⁇ obtain the lens action desired.
  • the insulator 8 at. the point of greatest potential gradient, its point oif contact with ⁇ the center electrode 3, is.- made thicker thanat any ⁇ other point to inhibit electrical breakdown by rupture of the insulatingmaterial.
  • the structure Vof the assembly orf Figs. 3, 4 is made asymmetrical, the outer electrode Il' being made planar and the intermediate electrode I8 and outer electrode I8 ibeing providedwith asymmetrical centrally positioned cup-shaped portions.
  • These electrodes are assembled Within the cylinder I and employ the same ⁇ insulators 8--I0 which arek used inthe assembly of.l ig. 1 t0y provide both Yaxial alignment ofrthe respective electrodes and centering ofthe intermediate electrode I8.
  • thi-s assembly I have shown theretaining ring I3 andscrew 11i aspositioned at the end closer to the apertures of the electrodes in order that an object tobe examined may be ⁇ positioned as closeto the-aperture 5 as ispossible.
  • the sleeve lI5 is therefore positioned atthe yopposite end of they assembly.
  • An important advantage of my improved lens assembly is that the dimensions ofthe insulators employed for supporting and aligning the elec.- trodes needbe accurate in one direction only.
  • the insulator 8 requires accurate dimen- ⁇ sioning only of itsouter diameter and of the surface I2 while the insulators 9, I0 are accurately dimen'sioned in length only.
  • a pair of offset lenses in conjunction with la combination of such insulating cylinders, and by controlling the amount of offset, a long electrical leakage path between electrodes is provided.
  • the assembly of insulators provides accurate centering with respect to the optical axis and accurate spacing axially of the respective electrodes. In this fashion, not'l only are the electrical characteristics of the system, so far as breakdown is concerned, improved, but at the same time the Ioptical properties of the lens are enhanced.
  • An electrostatic electronY lens 'structure comprising a sup-porting cylinder, three circular electrodes arranged 4coaxially within said cylinder and provided with lcentral apertures, theA outer of said electrodes being supported directly. by.
  • first insulating means of accurately di,-v mensioned thickness for supporting the inter-A mediate ofsaid electrodes within-.said cylinder and for aligning fthe apertures thereof withI the apertures of said outer electrodes, and-additional insulating means of accuratelyV dimensionedlength positioned between saidouter electrodes.
  • rstinsu-lating means4 of accurately dimensioned thickness for. supporting the intermediate of said electrodes within said cylinder and for aligning the apertures thereof with the apertures of said -outer electrodes,y and' additional insulating means of accurately dimensioned length positioned between said outer yelectrodes and said intermediate electrode fory spacing said electrodes axially within said cylin-. der.
  • An electrostatic electron lens structure comprising a Isupporting cylinder, three circularlyV symmetrical electrodes arranged coaxiallywithin said cylinder, the outer of said electrodes being supported directly by said cylinder and having their apertures aligned thereby, means includingy an insulator of accurately dimensioned thickness for centering the intermediate of said-electrodes on the optical axis of said structure andfcr aligning the apertures thereof with theapertures of said outer electrodes, 4and means includinga pair of insulators of accurately dimensioned length positioned between said ⁇ outer electrodes andjsaid ⁇ intermediate electrode ⁇ for aligning said electrodes 'axially of said cylinder.
  • An electron lens comprising a supporting ⁇ cylinder, threegcircularly symmetrical electrodesV spaced coaxia-lly within said cylinder, the outer 6 of said electrodes lbeing supported directly by said cylinder and having their 'apertures aligned REFERENCES CITED thereby, two of said electrodes having centrally y
  • the following references are of record ln the located oiset portions extending toward the third file 0f this Patenti of said electrodes, mean-s including an insulator l of accurately dimensione'd ⁇ r thickness for center- UNITED STATES PATENTS ing the intermediate of said electrodes with re- Number Name Date spect to the opti-cal axis 'of said lens, and means y 2,170,663 Painter v Aug.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Electron Tubes For Measurement (AREA)
US673218A 1946-05-31 1946-05-31 Electron lens assembly Expired - Lifetime US2452893A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FR957324D FR957324A (d) 1946-05-31
BE480180D BE480180A (d) 1946-05-31
US673218A US2452893A (en) 1946-05-31 1946-05-31 Electron lens assembly

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US673218A US2452893A (en) 1946-05-31 1946-05-31 Electron lens assembly

Publications (1)

Publication Number Publication Date
US2452893A true US2452893A (en) 1948-11-02

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US (1) US2452893A (d)
BE (1) BE480180A (d)
FR (1) FR957324A (d)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665384A (en) * 1950-07-18 1954-01-05 Hubert P Yockey Ion accelerating and focusing system
US2719243A (en) * 1951-07-03 1955-09-27 Du Mont Allen B Lab Inc Electrostatic electron lens
US2759117A (en) * 1952-05-16 1956-08-14 Farrand Optical Co Inc Electron lens
US2881347A (en) * 1954-08-31 1959-04-07 Sylvania Electric Prod Electronic tube packet
US4663532A (en) * 1984-12-14 1987-05-05 Commissariat A L'energie Atomique Apparatus for irradiating material by an electron beam
US20020036264A1 (en) * 2000-07-27 2002-03-28 Mamoru Nakasuji Sheet beam-type inspection apparatus

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170663A (en) * 1935-03-30 1939-08-22 Rca Corp Electron discharge device
US2184821A (en) * 1937-02-11 1939-12-26 Lorenz C Ag Braun tube
US2185807A (en) * 1937-04-30 1940-01-02 Gen Electric Cathode ray tube
US2330930A (en) * 1941-04-30 1943-10-05 Rca Corp Scanning type of electron microscope
US2347965A (en) * 1942-01-29 1944-05-02 Rca Corp Art of electron microscopy
US2400332A (en) * 1944-09-27 1946-05-14 Gen Electric Self-adjusting electrode support

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170663A (en) * 1935-03-30 1939-08-22 Rca Corp Electron discharge device
US2184821A (en) * 1937-02-11 1939-12-26 Lorenz C Ag Braun tube
US2185807A (en) * 1937-04-30 1940-01-02 Gen Electric Cathode ray tube
US2330930A (en) * 1941-04-30 1943-10-05 Rca Corp Scanning type of electron microscope
US2347965A (en) * 1942-01-29 1944-05-02 Rca Corp Art of electron microscopy
US2400332A (en) * 1944-09-27 1946-05-14 Gen Electric Self-adjusting electrode support

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665384A (en) * 1950-07-18 1954-01-05 Hubert P Yockey Ion accelerating and focusing system
US2719243A (en) * 1951-07-03 1955-09-27 Du Mont Allen B Lab Inc Electrostatic electron lens
US2759117A (en) * 1952-05-16 1956-08-14 Farrand Optical Co Inc Electron lens
US2881347A (en) * 1954-08-31 1959-04-07 Sylvania Electric Prod Electronic tube packet
US4663532A (en) * 1984-12-14 1987-05-05 Commissariat A L'energie Atomique Apparatus for irradiating material by an electron beam
US20020036264A1 (en) * 2000-07-27 2002-03-28 Mamoru Nakasuji Sheet beam-type inspection apparatus
US20050092921A1 (en) * 2000-07-27 2005-05-05 Ebara Corporation Sheet beam-type inspection apparatus
US7049585B2 (en) * 2000-07-27 2006-05-23 Ebara Corporation Sheet beam-type testing apparatus
US20060138343A1 (en) * 2000-07-27 2006-06-29 Ebara Corporation Sheet beam-type testing apparatus
US7109484B2 (en) 2000-07-27 2006-09-19 Ebara Corporation Sheet beam-type inspection apparatus
US7417236B2 (en) 2000-07-27 2008-08-26 Ebara Corporation Sheet beam-type testing apparatus
US20080302963A1 (en) * 2000-07-27 2008-12-11 Ebara Corporation Sheet beam-type testing apparatus
US7829871B2 (en) 2000-07-27 2010-11-09 Ebara Corporation Sheet beam-type testing apparatus

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Publication number Publication date
FR957324A (d) 1950-02-18
BE480180A (d)

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