US3889144A - Image intensifier tube - Google Patents

Image intensifier tube Download PDF

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Publication number
US3889144A
US3889144A US308725A US30872572A US3889144A US 3889144 A US3889144 A US 3889144A US 308725 A US308725 A US 308725A US 30872572 A US30872572 A US 30872572A US 3889144 A US3889144 A US 3889144A
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US
United States
Prior art keywords
phosphor screen
photocathode
potential
phosphor
electrode
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
US308725A
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English (en)
Inventor
James Dwyer Mcgee
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.)
Electron Physics Ltd
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Electron Physics Ltd
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Filing date
Publication date
Application filed by Electron Physics Ltd filed Critical Electron Physics Ltd
Application granted granted Critical
Publication of US3889144A publication Critical patent/US3889144A/en
Anticipated expiration legal-status Critical
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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
    • H01J31/503—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output with an electromagnetic electron-optic system

Definitions

  • This invention relates to a photoelectronic image intensifer tube.
  • a photoelectronic image intensifier has been proposed where an optical image is focused on to a plane photocathode in a high-vacuum tube and the resulting liberated photoelectrons are accelerated in a uniform electric field to a plane parallel target coated with a conventional phosphor screen.
  • the photoelectron stream is focused to form an electron image on this target by means of a uniform axial magnetic field the lines of force of which coincide as accurately as possible with those of the electric field.
  • n is the integral number of cycloidal loops made by the electrons between the photocathode and the phosphor screen. It is necessary to operate the device with a voltage of lO kV betweenphotocathode and screen to obtain an adequate light-gain, and hence even with n 1 the product B d 10 Thus even for a moderate magnetic field of I Gauss the spacing d must be 10 cm. In general there must be at least three such sections in cascade and hence the tube is rather inconveniently long.
  • an image intensifier tube having at least one stage com prising a phosphor screen spaced from a parallel photocathode and between which is provided a means transparent to electrons for producing a substantially equipotential surface in a plane substantially parallel the phosphor screen, the plane being relatively nearer the phosphor screen that the photocathode.
  • FIG- URE shows an image intensifier tube.
  • a phosphor screen 1 is mounted at one end of a cylindrical glass tube 2 which is surrounded by a coil 3 for producing an axial magnetic field B.
  • a photocathode 4 is provided at the other end of the tube parallel to the phosphor screen 1.
  • a very fine metal mesh 5, having for example 1000 meshes/in with a shadow rating of 20%, is placed at a relatively small distance from the phosphor screen 1. Typically the distance from the phosphor screen 1 to the mesh 5 may be 5 mm. and the distance from the mesh 5 to the photocathode 4 may be 2 cms.
  • a relatively low voltage of 100 V is applied between the mesh 5 and the photocathode 4 to cause photoelectrons to travel relatively slowly to the mesh 5.
  • the coil 3 produces a field B in the order of 50 Gauss which causes the electrons to execute 97% of their focusing cycloid before arriving at the mesh 5.
  • a large potential difference, in the order of kV is applied between the mesh 5 which provides an equipotential surface and the phosphor screen 1. The electrons are thus accelerated to the full 10 kV energy required before striking the screen 1 and they also complete the remaining 3% of their focusing cycloid during this time.
  • the technique described may be applied to several such intensifying stages in cascade.
  • Image intensifier tube apparatus comprising a phoshpor screen, a photocathode spaced from and parallel to said phosphor screen, a fine wire electrode for producing a substantially equipotential surface in a plane substantially parallel to said phosphor screen.
  • said plane being disposed intermediate said phosphor screen and said photocathode at a distance from said phosphor screen which is equal to or less than onefourth of the distance between said photocathode and said phosphor screen, means for applying a first potential between said photocathode and said electrode and a second potential between said electrode and said phosphor screen, said first potential being relatively small with respect to said second potential and means for establishing a magnetic field transverse to said plane to focus photoelectrons emitted from said photocathode onto said phosphor screen, said disposition of said plane and said relation between said first and second potentials causing a major portion of magnetic focusing to occur in a region of relatively low electric field strength.
  • Image intensifier tube apparatus comprising a plurality of phosphor screens, a plurality of photocathodes spaced from and parallel to said plurality of phosphor screens, and a plurality of fine wire electrodes for producing substantially equipotential surfaces in planes substantially parallel to saidphosphor screens, each of said plurality of photocathodes, electrodes and phosphor screens forming an element of a stage of image intensifier tube apparatus employing a plurality of stages in cascade formation, each of said planes being disposed intermediate related ones of said plurality of phosphor screens and photocathodes at a distance from said phosphor screen which is equal to or less than onefourth of the distance between said photocathode and said phosphor screen, means for applying a first potential between said related photocathodes and an associated electrode and a second potential between said associated electrode and said related phosphor screen, said first potential being relatively small with respect to said second potential and means for establishing a magnetic field transverse to said planes to focus photoelectrons emitted form each

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US308725A 1971-11-24 1972-11-22 Image intensifier tube Expired - Lifetime US3889144A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5455471 1971-11-24

Publications (1)

Publication Number Publication Date
US3889144A true US3889144A (en) 1975-06-10

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ID=10471395

Family Applications (1)

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US308725A Expired - Lifetime US3889144A (en) 1971-11-24 1972-11-22 Image intensifier tube

Country Status (5)

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US (1) US3889144A (enrdf_load_stackoverflow)
JP (1) JPS4864870A (enrdf_load_stackoverflow)
DE (1) DE2257215A1 (enrdf_load_stackoverflow)
FR (1) FR2161065A1 (enrdf_load_stackoverflow)
NL (1) NL7215770A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4163174A (en) * 1977-06-13 1979-07-31 International Telephone & Telegraph Corp. Oblique streak tube
US4220890A (en) * 1977-03-28 1980-09-02 U.S. Philips Corporation Magnetic shielding for an X-ray image intensifier tube
EP0136752A3 (en) * 1983-09-05 1986-12-30 Philips Electronic And Associated Industries Limited Electron image projector

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2092814A (en) * 1935-03-01 1937-09-14 Aeg Photoelectric tube
US2941100A (en) * 1957-03-06 1960-06-14 Itt Cathode ray tube
US3141105A (en) * 1963-12-19 1964-07-14 American Optical Corp Cathode ray tube with composite multiple glass fibre face
US3254252A (en) * 1962-01-24 1966-05-31 Westinghouse Electric Corp Image device
US3321659A (en) * 1963-12-12 1967-05-23 Westinghouse Electric Corp Radiation sensitive electron emissive device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2092814A (en) * 1935-03-01 1937-09-14 Aeg Photoelectric tube
US2941100A (en) * 1957-03-06 1960-06-14 Itt Cathode ray tube
US3254252A (en) * 1962-01-24 1966-05-31 Westinghouse Electric Corp Image device
US3321659A (en) * 1963-12-12 1967-05-23 Westinghouse Electric Corp Radiation sensitive electron emissive device
US3141105A (en) * 1963-12-19 1964-07-14 American Optical Corp Cathode ray tube with composite multiple glass fibre face

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4220890A (en) * 1977-03-28 1980-09-02 U.S. Philips Corporation Magnetic shielding for an X-ray image intensifier tube
US4163174A (en) * 1977-06-13 1979-07-31 International Telephone & Telegraph Corp. Oblique streak tube
EP0136752A3 (en) * 1983-09-05 1986-12-30 Philips Electronic And Associated Industries Limited Electron image projector

Also Published As

Publication number Publication date
FR2161065A1 (enrdf_load_stackoverflow) 1973-07-06
JPS4864870A (enrdf_load_stackoverflow) 1973-09-07
DE2257215A1 (de) 1973-05-30
NL7215770A (enrdf_load_stackoverflow) 1973-05-28

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