US3432668A - Photomultiplier having wall coating of electron emitting material and photoconductive material - Google Patents

Photomultiplier having wall coating of electron emitting material and photoconductive material Download PDF

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Publication number
US3432668A
US3432668A US586737A US3432668DA US3432668A US 3432668 A US3432668 A US 3432668A US 586737 A US586737 A US 586737A US 3432668D A US3432668D A US 3432668DA US 3432668 A US3432668 A US 3432668A
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United States
Prior art keywords
electron
tube
photomultiplier
light
photoconductive material
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Expired - Lifetime
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US586737A
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English (en)
Inventor
John R Davy
John M Ballantine
William B Allan
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JOHN M BALLANTINE
JOHN R DAVY
WILLIAM B ALLAN
Original Assignee
JOHN M BALLANTINE
JOHN R DAVY
WILLIAM B ALLAN
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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
    • H01J31/506—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect
    • H01J31/507—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect using a large number of channels, e.g. microchannel plates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/24—Dynodes having potential gradient along their surfaces
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2231/00—Cathode ray tubes or electron beam tubes
    • H01J2231/50—Imaging and conversion tubes
    • H01J2231/50005—Imaging and conversion tubes characterised by form of illumination
    • H01J2231/5001—Photons
    • H01J2231/50015—Light
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2231/00—Cathode ray tubes or electron beam tubes
    • H01J2231/50—Imaging and conversion tubes
    • H01J2231/50057—Imaging and conversion tubes characterised by form of output stage
    • H01J2231/50063—Optical
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2231/00—Cathode ray tubes or electron beam tubes
    • H01J2231/50—Imaging and conversion tubes
    • H01J2231/501—Imaging and conversion tubes including multiplication stage
    • H01J2231/5013—Imaging and conversion tubes including multiplication stage with secondary emission electrodes
    • H01J2231/5016—Michrochannel plates [MCP]

Definitions

  • An electron multiplier having varying amplification including a tube provided on the inner surface with a coat ing of electron-emitting material with the input end of the tube being provided with a second layer of photoconductive material so that amplification of an electron stream passing through the tube is dependent upon the amount of light striking the photoconductive material.
  • Image intensifiers have been proposed, in which an image is focussed on to a film of material which emits electrons when irradiated by photons, above a certain energy.
  • the material is basically a mixture of alkali metals. If the incident light is below the critical wavelength, then electrons are emitted from a point on the film in quantities which are proportional to the image intensity at that point. Thus the optical image is converted into an electron object.
  • the electrons are focussed, either electrostatically or magnetically, onto a phosphor screen and are accelerated towards this screen.
  • the electrons impinge on the phosphor and cause light to be emitted.
  • the image thus appears on the phosphor screen and its brightness is determined by the accelerating voltage applied to the electrons.
  • the phosphor emits light in the visible spectrum but the alkali screen can be made sensitive to light of wavelengths up to 1.2, approx. This means that an image in the near infrared can be converted to a visible image.
  • An alternative method of increasing the signal from a photon is employed in a photomultiplier.
  • the photon emits an electron from an alkali film, as above.
  • the electron is accelerated and strikes a dynode where secondary electrons are emitted.
  • These secondaries are accelerated onto a second dynode where more secondaries are ejected.
  • the original electron thus gives rise to a large number of secondary electrons, the number depending on the number and type of dynodes, and the accelerating voltages.
  • the electron multiplication section is a complicated set of metal structures fed by a chain resistor network.
  • the present invention is an electron multiplier comprising a tube having, on the inner surface thereof, a first layer of secondary electron-emitting, electrically conducting material and, adjacent one end, the input end, a second layer of photoconductive material, terminal means being provided for connecting a source of voltage along the tube and in series with said layers whereby the amplification of an electron stream passing down the tube may be made dependent on the amount of light striking the layer of photoconductive material.
  • the present invention is also an image intensifier or converter comprising an evacuated tubular shell having at one end an input window and at the other end detector means, at least one electron multiplier as defined 3,432,668 Patented Mar. 11, 1969 in the last preceding paragraph mounted intermediate the ends of the tube, first means for providing a background stream of electrons mounted in the tube adjacent the window and second means for maintaining the first means at the same potential as the input end of the electron multiplier.
  • FIG. 1 is a perspective view of an image intensifier according to the present invention, part of the outer shell of the image intensifier being broken away to show the internal components;
  • FIG. 2 is a detailed, enlarged view of an electron multiplier as used in the image intensifier of FIG. 1.
  • an image intensifier 10 consists of an evacuated tubular shell 11 having an input window 12 at one end and detector means in the form of a phosphor screen 13 at the other end.
  • a long half-life ,9 emitter in the form of a ring 14 is provided immediately behind the input window 12 to pro-v vide a background stream of electrons.
  • a bundle 15 of electron multipliers 15, one of which is illustrated in FIG. 2, is also mounted in the shell 11 and terminates a short distance from the phosphor screen 13.
  • Three voltage leads 17 are provided, one to each end of the bundle 15 and one to the phosphor screen 13, to be connected to a voltage source 18 as shown.
  • the inner surface of the shell 11 is provided, between ring 14 and the input end of the bundle 15, with a metal coating 19 to maintain the ring 14 at the same electrical potential as the input end of the bundle, i.e. the left-hand end of FIG. 1.
  • each multiplier 16 has a diameter small enough to be below the resolution of a detecting device, e.g. a human eye, at the phosphor screen.
  • Each electron multiplier 16 consists of a glass tube 24 coated on its inner surface with a secondary electron emitter electrically conducting material 25, in this embodiment silicon.
  • Adjacent the input end of the electron multiplier, i.e. the left hand in FIG. 2 is provided a second layer 26 of photoconductor material.
  • the layer 26 is of lead sulphide and, as the input window should be made from a material transparent through the sensitive region of the photoconductor, the input window 12 is made of sapphire or calcium acetate.
  • the ends of the electron multipliers are rendered conducting by evapourating on to them a suitable metal 28, e.g. aluminium, to allow for connection of the ends of the bundle 15 to the appropriate voltage leads 17'.
  • the voltage across the electron emitter coating 25 will vary according to the intensity of this light and therefore the amplification of the electron beam will vary with the intensity of the light.
  • the increase in voltage across the coating 25 is not linear with light input, but the electron gain provided by the coating 25 is not linear with applied voltage and it is possible to choose the parameters such that the gain of the coating 25 changes linearly with alteration in light input.
  • the phosphor screen 13 of course, converts the electron beam into visible light and its output intensity also varies in sympathy with the intensity of the incident light.
  • image converters or intensifiers may be made that are sensitive over the wavelength range of photo-conductors. This frees such devices from the stigma of very limited sensitivity of the electron emitter materials in the 1 micron range.
  • An electron multiplier comprising a hollow tube having an inner surface and an input end and an output end, a first layer of secondary electron-emitting electrically conducting material on said inner surface, a second layer of photoconductive material adjacent said input end, terminal means connecting a source of voltage along the tube and in series with said layers, so that the amplification of an electron stream passing down the tube is dependent on the amount of light striking the layer of photo-conductive material.
  • An image intensifier or converter comprising an evacuated tubular shell having at one end an input window and at the other end detector means, at least one electron multiplifier comprising a hollow tube haivng an inner surface and an input end and an output end, a first layer of secondary electron-emitting electrically conductive material on said inner surface, a second layer of photoconductive material adjacent said input end, terminal means connecting a source of voltage along the tube and in series with said so that the amplification of an electron stream passing down the tube is dependent upon the amount of light striking the layer of photoconductive material, said electron multiplier being mounted intermediate the ends of the tubular shell, first means for providing a background stream of electrons mounted in the tubular shell adjacent the window and second means for maintaining the first means at the same potential as the input end of the electron multiplier.

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  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US586737A 1965-10-15 1966-10-14 Photomultiplier having wall coating of electron emitting material and photoconductive material Expired - Lifetime US3432668A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB43912/65A GB1118331A (en) 1965-10-15 1965-10-15 Improvements in electron multipliers and image intensifiers or converters

Publications (1)

Publication Number Publication Date
US3432668A true US3432668A (en) 1969-03-11

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US586737A Expired - Lifetime US3432668A (en) 1965-10-15 1966-10-14 Photomultiplier having wall coating of electron emitting material and photoconductive material

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US (1) US3432668A (US07714131-20100511-C00038.png)
GB (1) GB1118331A (US07714131-20100511-C00038.png)
NL (1) NL6614500A (US07714131-20100511-C00038.png)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634690A (en) * 1970-03-23 1972-01-11 Itt Tubular photocell with secondary emission from internal surface
US4333035A (en) * 1979-05-01 1982-06-01 Woodland International Corporation Areal array of tubular electron sources
US4438557A (en) * 1979-05-01 1984-03-27 Woodland International Corporation Method of using an areal array of tubular electron sources

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1046127A (en) * 1974-10-14 1979-01-09 Matsushita Electric Industrial Co., Ltd. Secondary-electron multiplier including electron-conductive high-polymer composition
JPS6013257B2 (ja) 1976-02-20 1985-04-05 松下電器産業株式会社 二次電子増倍体およびその製造方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3128408A (en) * 1958-09-02 1964-04-07 Bendix Corp Electron multiplier

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3128408A (en) * 1958-09-02 1964-04-07 Bendix Corp Electron multiplier

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634690A (en) * 1970-03-23 1972-01-11 Itt Tubular photocell with secondary emission from internal surface
US4333035A (en) * 1979-05-01 1982-06-01 Woodland International Corporation Areal array of tubular electron sources
US4438557A (en) * 1979-05-01 1984-03-27 Woodland International Corporation Method of using an areal array of tubular electron sources

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Publication number Publication date
NL6614500A (US07714131-20100511-C00038.png) 1967-04-17
GB1118331A (en) 1968-07-03

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