US2412687A - Electron lens - Google Patents

Electron lens Download PDF

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Publication number
US2412687A
US2412687A US528994A US52899444A US2412687A US 2412687 A US2412687 A US 2412687A US 528994 A US528994 A US 528994A US 52899444 A US52899444 A US 52899444A US 2412687 A US2412687 A US 2412687A
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United States
Prior art keywords
electrodes
electrode
lens
electron
edges
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Expired - Lifetime
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US528994A
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English (en)
Inventor
Klemperer Otto Ernst Heinrich
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EMI Ltd
Electrical and Musical Industries Ltd
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EMI Ltd
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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
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/62—Electrostatic lenses

Definitions

  • the present invention relates to electrode systems for producing electron lenses such as are employed in cathode ray tubes, electron discharge valves and other electron discharge devices for focusing electron beams and to electron discharge v. devices including such systems.
  • An electrode system for producing an electron lens is usually disposed symmetrically about an axis and affords a passage through which the beam to be acted on is projected.
  • the electrode system may comprise two axially aligned plane diaphragm electrodes having central apertures defining said passage or tubular electrodes embracing said passage with their ends or transverse edges included in planes perpendicular to the axis,
  • Figures 1A and 1B of the accompanying drawing are each diagrammatic side elevational Views of known systems of tubular electrodes, each comprising two aligned tubular electrodes A and B respectively, through which the beam to be acted upon is projected.
  • electrodes A and B are maintained at different potentials V1, V2, respectively, the electron lens so produced will be converging whichever electrode is the more positive and whether or not an electron beam is projected from left to right or from right to left through the system.
  • the focal length of the lens will depend on the ratio of the voltages applied to the electrodes A and B with respect to the cathode of the beam operated upon.
  • electrodes A and B may lbe of the same diameter so that the edges of the electrodes are in registry, the electrodes being separated by a gap G having an axial length sumcient to provide an adequate insulation between the two electrodes.
  • the mid-surface of the lens is defined as the surface including the inner edge or edges cf the aforesaid end of the smaller
  • the mid-surface of the lens is constituted by the plane of the aforesaid end of the smaller ⁇ diameter electrode, this plane being represented by the line M in Figure 1B.
  • the electrodes A and B may be of circular, rectangu lar, square, elliptical or other desired cross-section having axial symmetry, or they may each comprise a pair of oppositely disposed elements, for example of plate form.
  • the midsurface of the lens is defined, as the surface midway Ibetween the facing surfaces of the diaphragm electrodes.
  • the mid-surface is again also a plane;
  • the field produced is equivalent to that of several pairs in combination, and the system may be treated as producing a combination of separate lenses each constituted between one electrode and the next in succession along the axis.
  • the mid-surface may be dened as the surface midway between the surfaces including the inner edges or facing surfaces as the case may be of the outermost electrodes, but the arrangement can also be regarded as composed of a pair of lenses constituted by the electrostatic fields in the gaps between the electrodes.
  • the present invention arises out of an investigation for the purpose of providing improved electrode systems for producing electron lenses ⁇ for focusing an electron beam in a, line, for example as required in certain kinds of electron discharge valves for high frequency operation, for example, in devices of the kind known as Klystrons.
  • an electrode system for formingan electron lens compri-sing two aligned cooperating electrodes affording an unobstructed passage for anelectron beam to be acted upon, and having the inner edge or edges or each electrode presented to the inner edge or edges of the other, said edge or edges being so curved that the mid-plane of said lens is curved.
  • an electrode system for forming an electron len-s comprising two aligned col-operating electrodes affording an unobstructed passage for an electron beam and of which one electrode is of smaller diameter than the other and'has one end inserted within the other, the edge of said end being so curved that the midplane of said lens is curved.
  • an electrode system for forming an electron lens comprising. a pair of apertured diaphragm electrodes disposed with their apertures aligned to afford an unobstructed passage for Van electron' beam, said electrodes having their facing surfaces so curved that the mid-plane of said lens is curved.
  • the invention also includes electron discharge apparatus having an electrode system as above set forth and means for projecting an electron beam through said passage and means for maintaining the electrodes of said system at such potentials that said beam i-s acted upon in a desired manner.
  • Another object is to provide an improved method of and means for reducing aberration in an electron lens.
  • a further object is to provide an improved i method of and means for deriving a line image of anelectron source.
  • An additional object of the invention is to prov vi-de an improved electron lens having a curved ⁇ Figures 2 to i0 of the accompanying drawing, of
  • FIG. 3 isa perspective view of an electrode for use in a further electrode system according to the invention
  • Figures 4A and 4B are plan and elevational view-s respectively of an electrode system according to the invention including cylindrical electrodes,
  • Figure 4D is a plane development of the electrode ofv Figure 4C
  • Figure 8 illustrates a construction of an electrode for use in the system in accordance with the invention of which the 1ens-forming elements are of diaphragm form, and
  • Figures 9 and 10 show two electrode systems formed in accordance with the invention and each including more than two lens-forming electrodes.
  • the system shown in Figure 2 comprises a pair cf electrodes A and B aligned and having their sides in registry and aifording a passage of uniform rectangular cross-section throughout their length.
  • the electrodes are separated by a gap G to isolate them electrically from one another.
  • the electrode A has horizontal sides l and 2 and vertical side-s 3 and li, while the electrode B has horizontal sides 5 and E and vertical sides and 8.
  • the horizontal sides of the electrodes A and Bare represented as being wider than the vertical sides, but for some applications, the sides may all be of the same width so that the cross-section of the electrodes is square or the vertical ⁇ sides may be Wider than the horizontal sides.
  • the inner ends of the vertical sides 3, i and l, 8 of the electrodes A and B are formed with curved edges to constitute an electron lens having a curved mid-surface.
  • the curved edges are cut to conform to cylindrical surfaces of radius R having their axes perpendicular to the axis of the electrode system, the curved edges on electrode A being recessed and the curved edges on electrode B being convex and complementary to those of electrode A.
  • the mid-surface of the electron lens will then be a cylindrical surface of radius R located in the middle of the gap G.
  • V electrode B If theV electrode B is maintained at a higher positive potential than the electrode A, a parallel will cause a beam projected through it in either direction to diverge.
  • FIG. 3 shows a perspective View of an electrode B' which corresponds to the electrode B of Figures 1 and 2, but which has the edges of its wide sides 5, 6 cut away or recessed toconforrn to a cylinder of radius RI.
  • the curvature of the midsurface of the lens is identical with that of the surface in which the curved inner edges of the lens-forming electrodes A and B or A and B are located, but it is not essential that this should -be so.
  • the curvature of the inner edgesof the electrodes may be made to diier so that the curvature of the mid-surface is different from that of the edges of either electrode.
  • the radius of the mid-surface will be equal to the mean of the radii of the adjacent edges.
  • the inner edges of the electrodes A and B need not conform-Ito cylindrical surfaces.
  • the electrode system shown comprises a pair of electrodes A and B having their edges formed with diametrically opposed projecting portions II, I 2 or I3, I4 as the case may be, the edges being complementary.
  • the electrodes A and B" are identical in form, the single electrode B" being shown in Figure 4C and a plane development of this electrode is shown in Figure 4D.
  • the projecting portions I3 and I4 are formed by cutting the edge of the electrode to conform to a series of semicircular arcs I 5, I6, II and I8 each of radius equal to an eighth of the circumference'of the tube, the arcs being alternatively convex and recessed.
  • the electrodes may be formed by severing a single flat sheet of material along the line of the arcs I5 to I8 and rolling the two severed portions of the sheet to provide the electrodes.
  • the length of the focal line may be greater than the original diameter of the beam and the beam may be divergent in directions parallel to the plane, and, in fact, with the construction of electrodes described with reference to Figures 4C and 4D, the divergency of the focused beam is such that the focal line will have a length of the order of twice the diameter of the original beam. If it is desired that the beam shall not be divergent, or should be of different divergency the inner edges of electrodes A" and B" can be shaped accordingly.
  • the arcs are not made semi-circular, but are given a radius 21rRr approximately, a system which produces practically no divergency of the beam will be produced.
  • the focal length of the system will be increased however, and also the aberration propoint focus wouldbe obtained. From this it will be appreciated that if the radii of the aforesaid arcs are greater than 21rRT the beam will con- VergeV after passing through the lens systems Asuitable for use in cathode Yray guns.
  • a cylindrical electrode such as A lof Figure 6 or a square section electrode such as ,'A of Figure 7 is employed will depend on which electrode is the more suitable for incorporation in posed at different distances fromthemid-surface and in planes at right angles to each other.
  • a satisfactory focusing of a rib-- bon shaped beam may be obtained with complementary cylindrical tubular electrodes formed in the manner illustrated at A" in Figures A and 5B with straight edge portions l2l and 22 alternately with arcuate portions either convex as shown at 23 and 24 in Figures 5A and 5B or concave. trodes constructed in this manner is no-tthought to have a very wide application. It is believed that having regard to the description already given with regard to the system of Figures 4A and 4B, the Inode of operation of a system employing electrodes formed in the manner indicated with reference to Figures 5A and 5B will be understood without difficulty.
  • Figures 6 and 7 of the drawing show theapplication of the invention to lens systems of the kind described above with reference to Figure 1B, in which the lens eld is formed at the end of a tubular electrode inserted withinanother electrodeof larger diameter.
  • the system is constituted by co-operating cylindrical electrodes A and C, the electrode A" having one end formed with projecting portions Il and l2 in the manner described with reference to Figures 4C and 4D above, and having this end inserted within the larger diameter electrode C, shown partly broken away to show the ⁇ disposition of parts within its interior.
  • rheelectrode-C may be constituted by a conducting coating on the neckof a cathode ray tube for example.
  • Figure 7 shows an arrangement similar to that shown in Figure 6 but in which the cylindrical electrode A" is replaced by an electrode A of square cross-section, and the inner end of which is formed with semi-circular edges in the manner described with reference to Figure 3 above.
  • the effect of the square section electrode A is substantially the same as that of a tubular electrode such as A" of Figure 6 of a diameter equal to the length of the side of the square cross-section, and i it will be appreciated that the curvatures of the inner ends of the electrodes A and A of Figures 6 and 7 can be varied 'in the manner indicated with-.reference to Figures 4A and'4B above, the lens being diverging or converging or substantially ineifective in planes parallel vto the plane of symmetry between the projecting portions of the electrode according to the curvature of the edges of electrode A or A" as the case may be.
  • a lens system formed of elec- Preferably the electrode A" .i
  • Figure 6 the construction of Figure 6 being particularly .by a diaphragm 28, constituting the lens-forming element, the diaphragm being curved to conform to a cylindrical surface and havingv a slot 29 eX- tending parallel to its curved edges.
  • This electrode may be arranged to co-operate with a similarly formed electrode but with the end carrying the diaphragm recessed and curved in a manner complementary to the curvature of the end of the electrode D.
  • diaphragms' such as 28 might be constituted simply by elements in the form of strips separated by a gap corresponding to the slot 2:23, and the shield portion 2! might be omitted.
  • Figures 9 and 10 show the electrode systems for producing a plurality of lenses having mid-surfaces curved in accordance with the invention.
  • the arrangement of Figure 7 includes three electrodes 3E?, 3
  • the potentials V1, V2, V3, respectively, of the electrodes B, 3l and 32 may be arranged to increase or decrease successively, or the electrode 3i may be at a more positive or less positive potential than either of the electrodes 30 and 32. If the potential of the electrode 3
  • Figure 8'an electrode system is shown comprising five electrodes 35, 36, 3?, 33, 39, separated by gaps 4U, 4l, 42, 43, the electrodes being formed with curved edges in accordance with the invention.
  • the potentials V1, V2, Va, V4, V5, respectively, of these electrodes may be arranged to increase or decrease successively to provide a series of similar lenses.
  • an electrode system for forming an electron lens comprising two aligned co-operating electrodes "affording an unobstructed passage for an electron beam to be acted upon, and having the inner edges of each electrode presented to the adjacent inner edges of the other of said electrodes, said edges being differently lcurved with Y respect to each other to provide a curved lens mid-plane, the curvature of said mid-plane being related to the shape of said electrodes to minimize spherical aberration in said lens.
  • each of said electrodes comprises a pair of parallel disposed plane elements disposed symmetrically on opposite sides of said passage, said adjacent inner edges of each of said pairs of said elements being curved t0 determine said mid-plane curvature.
  • An electrode system for forming an electron lens comprising two aligned co-operating electrodes affording an unobstructed passage for an electron beam and of which one electrode is of smaller diameter than the other and has one end inserted within the other, the edge of said inserted end of said smaller diameter electrode being curved to provide a curved lens mid-plane, the curvature of said mid-plane being related to the shape of said electrodes to minimize spherical aberration in said lens.
  • An electrode system of the type described in claim 1 including means for applying focusing potentials to said electrodes, and wherein said lens mid-plane curvature provides an electron image forming a line transverse to the axis of said electron beam.
  • An electrode system of the type described in claim 5 including means for applying focusing potentials to said electrodes, and wherein said lens mid-plane curvature provides an electron image forming a line transverse to the axis of said electron beam.
  • An electrode system of the type described in claim 8 including means for applying focusing potentials to said electrodes, and wherein said lens midplane curvature provides an electron image forming a line transverse to the axis of said electron beam.
  • An electrode system of the type described in claim 12 including means for applying focusing potentials to said electrodes, and wherein said lens mid-plane curvature provides an electron image forming a line transverse to the axis of said electron beam.

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  • Electron Beam Exposure (AREA)
US528994A 1942-04-08 1944-03-31 Electron lens Expired - Lifetime US2412687A (en)

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Application Number Priority Date Filing Date Title
GB4628/42A GB574056A (en) 1942-04-08 1942-04-08 Improvements in electron lenses

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US2412687A true US2412687A (en) 1946-12-17

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US (1) US2412687A (enrdf_load_stackoverflow)
FR (1) FR922408A (enrdf_load_stackoverflow)
GB (1) GB574056A (enrdf_load_stackoverflow)
NL (1) NL82605C (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455676A (en) * 1946-05-21 1948-12-07 Rca Corp Electron lens correction device
US2647213A (en) * 1946-06-14 1953-07-28 Atomic Energy Commission Isotope separating apparatus
US2827585A (en) * 1953-12-15 1958-03-18 Philips Corp Cathode-ray tube apparatus
US2862129A (en) * 1954-03-11 1958-11-25 Philips Corp Device for compensating the astigmatism of electron lenses
US3678316A (en) * 1967-11-11 1972-07-18 Philips Corp Plural beam cathode ray tube having boundary-shaped cylindrical electrodes correcting beam aberration
DE2223369A1 (de) * 1972-01-14 1973-07-19 Rca Corp Mehrstrahl-kathodenstrahlroehre
US3873879A (en) * 1972-01-14 1975-03-25 Rca Corp In-line electron gun
DE2800066A1 (de) * 1977-01-06 1978-07-20 Tektronix Inc Elektronenstrahlroehre
DE2811355A1 (de) * 1977-04-18 1978-10-19 Tektronix Inc Geraet mit einer kathodenstrahlroehre
US4302704A (en) * 1978-10-18 1981-11-24 Iwatsu Electric Co., Ltd. Postacceleration cathode ray tube with a scan expansion lens
FR2538613A1 (fr) * 1982-12-27 1984-06-29 Tektronix Inc Ensemble de lentilles electrostatiques d'acceleration et d'expansion de balayage
FR2544549A1 (fr) * 1983-04-12 1984-10-19 Iwatsu Electric Co Ltd Tube a rayons cathodiques avec une lentille electronique pour l'amplification de la deviation
US4623819A (en) 1985-08-12 1986-11-18 Tektronix, Inc. Accelerating and scan expansion electron lens means for a cathode ray tube
US20090121149A1 (en) * 2007-11-09 2009-05-14 Varian Semiconductor Equipment Associates, Inc. Techniques for shaping an ion beam

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7607722A (nl) * 1976-07-13 1978-01-17 Philips Nv Astigmatische elektronenlens, kathodestraal- buis met een dergelijke lens en inrichting met een dergelijke kathodestraalbuis.

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2455676A (en) * 1946-05-21 1948-12-07 Rca Corp Electron lens correction device
US2647213A (en) * 1946-06-14 1953-07-28 Atomic Energy Commission Isotope separating apparatus
US2827585A (en) * 1953-12-15 1958-03-18 Philips Corp Cathode-ray tube apparatus
US2862129A (en) * 1954-03-11 1958-11-25 Philips Corp Device for compensating the astigmatism of electron lenses
US3678316A (en) * 1967-11-11 1972-07-18 Philips Corp Plural beam cathode ray tube having boundary-shaped cylindrical electrodes correcting beam aberration
US3678320A (en) * 1967-11-11 1972-07-18 Philips Corp Cathode ray tube having triangular gun array and curvilinear spacing between the fourth and fifth grids
DE2223369A1 (de) * 1972-01-14 1973-07-19 Rca Corp Mehrstrahl-kathodenstrahlroehre
US3772554A (en) * 1972-01-14 1973-11-13 Rca Corp In-line electron gun
US3873879A (en) * 1972-01-14 1975-03-25 Rca Corp In-line electron gun
US4137479A (en) * 1977-01-06 1979-01-30 Tektronix, Inc. Cathode ray tube having an electron lens system including a meshless scan expansion post deflection acceleration lens
DE2800066A1 (de) * 1977-01-06 1978-07-20 Tektronix Inc Elektronenstrahlroehre
US4188563A (en) * 1977-01-06 1980-02-12 Tektronix, Inc. Cathode ray tube having an electron lens system including a meshless scan expansion post deflection acceleration lens
DE2811355A1 (de) * 1977-04-18 1978-10-19 Tektronix Inc Geraet mit einer kathodenstrahlroehre
US4142128A (en) * 1977-04-18 1979-02-27 Tektronix, Inc. Box-shaped scan expansion lens for cathode ray tube
FR2388399A1 (fr) * 1977-04-18 1978-11-17 Tektronix Inc Lentille d'etalement du balayage, en forme de boite, pour tube a rayons cathodiques
US4302704A (en) * 1978-10-18 1981-11-24 Iwatsu Electric Co., Ltd. Postacceleration cathode ray tube with a scan expansion lens
FR2538613A1 (fr) * 1982-12-27 1984-06-29 Tektronix Inc Ensemble de lentilles electrostatiques d'acceleration et d'expansion de balayage
DE3346208A1 (de) * 1982-12-27 1984-07-05 Tektronix, Inc., Beaverton, Oreg. Elektrostatisches linsensystem sowie dessen verwendung in einer kathodenstrahlroehre
FR2544549A1 (fr) * 1983-04-12 1984-10-19 Iwatsu Electric Co Ltd Tube a rayons cathodiques avec une lentille electronique pour l'amplification de la deviation
US4623819A (en) 1985-08-12 1986-11-18 Tektronix, Inc. Accelerating and scan expansion electron lens means for a cathode ray tube
US20090121149A1 (en) * 2007-11-09 2009-05-14 Varian Semiconductor Equipment Associates, Inc. Techniques for shaping an ion beam

Also Published As

Publication number Publication date
NL82605C (enrdf_load_stackoverflow)
FR922408A (fr) 1947-06-09
GB574056A (en) 1945-12-19

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