EP0062553B1 - Cible de tube intensificateur d'image et tube intensificateur d'image à sortie vidéo muni d'une telle cible - Google Patents

Cible de tube intensificateur d'image et tube intensificateur d'image à sortie vidéo muni d'une telle cible Download PDF

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Publication number
EP0062553B1
EP0062553B1 EP82400460A EP82400460A EP0062553B1 EP 0062553 B1 EP0062553 B1 EP 0062553B1 EP 82400460 A EP82400460 A EP 82400460A EP 82400460 A EP82400460 A EP 82400460A EP 0062553 B1 EP0062553 B1 EP 0062553B1
Authority
EP
European Patent Office
Prior art keywords
target
layer
luminescent material
covered
target according
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
Application number
EP82400460A
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German (de)
English (en)
French (fr)
Other versions
EP0062553A1 (fr
Inventor
Jean-Pierre Galves
Daniel Gibilini
Henri Rougeot
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.)
Thales SA
Original Assignee
Thomson CSF SA
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
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0062553A1 publication Critical patent/EP0062553A1/fr
Application granted granted Critical
Publication of EP0062553B1 publication Critical patent/EP0062553B1/fr
Expired 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/44—Charge-storage screens exhibiting internal electric effects caused by particle radiation, e.g. bombardment-induced conductivity
    • 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
    • H01J31/49—Pick-up adapted for an input of electromagnetic radiation other than visible light and having an electric output, e.g. for an input of X-rays, for an input of infrared radiation

Definitions

  • the present invention relates to an image intensifier tube target. It also relates to image intensifier tubes with video output provided with such a target.
  • radiological image intensifier tubes commonly designated by the initials IIR, but it is understood that the invention also applies to light image intensifier tubes and scintigraphy image intensifier tubes (radiationy).
  • variable gain targets whose gain, that is to say the number of photons emitted for each electron received by the target, can be multiplied by a factor of around 100.
  • the I.I.R. can, as desired, operate in radiography or radioscopy.
  • the video output signal from the ILR. allows viewing on a television screen of the information contained in the X-ray beam reaching the I.I.R .; the television image is recorded on film or photo.
  • a good signal-to-noise ratio a high dose of X-rays must be sent during the short exposure time. It is therefore necessary to have a low gain target to avoid its saturation.
  • the electron beam 14 from the cathode of the ILR. arrives on the metallic barrier layer which slows it down and lets through only the higher energy electrons. These electrons cause in the luminescent layer the creation of photons which generates charge carriers in the target's silicon. These charge carriers discharge diodes, polarized in reverse, and being on the other face of the target; finally the distribution of the charges on the other face of the target is explored by the electron beam of a shooting tube which provides the video signal.
  • the gain variation of the target is obtained by varying the acceleration voltage of the beam of the ILR. and using the non-linear relationship that exists, for metallic barrier layers, between the penetration of electrons into the barrier layer and the acceleration voltage of the electron beam.
  • An image intensifier with a target which has a luminescent layer on the face directed towards a photocathode and the other face of which is scanned by a detection beam, is known from the article published in "Journal of the electrochemical Society” , Flight. 118, No. 4 (1971) pages 619 to 628.
  • the present invention relates to a variable gain target which overcomes these drawbacks.
  • the present invention relates to a variable gain target for an image intensifier tube with video output which receives on one of its faces the impact of an electron beam coming from the photocathode of the intensifier tube, while the other face of the target is scanned by an electron beam produced by the cathode of a shooting tube, the variation of the gain of the target being obtained by means making it possible to subject the electron beam coming from the photocathode to two different acceleration voltages, characterized in that the target comprises, on its face receiving the impact of the electron beam coming from the photocathode of the intensifier tube, two types of luminescent materials, of different light output and of indifferent color, which receive the impact of the electron beam, and means ensuring the excitation of the only luminescent material of lower light output by the electron beam subjected to the lower ac voltage celeration and ensuring the excitation of the luminescent material of higher light output by the electron beam subjected to the highest acceleration voltage.
  • the two luminescent materials of the target emit light of different wavelength and the target comprises an optical filter suitable which transmits more light emitted by the luminescent material with high light output than that emitted by the other luminescent material.
  • the two luminescent materials are carried by a wafer of optical fibers and a better resolution is obtained than in the case of the prior art where the target is made of silicon, covered with '' a luminescent layer and a metallic barrier layer.
  • FIG. 1 shows the diagram of an I.I.R. with video output which is generally designated by the reference 1.
  • An X-ray beam after passing through the body to be observed 3, enters the I.I.R. through a window 4.
  • the other face f 2 of the target 7 is scanned line after line by an electron beam produced by the cathode K, heated by a filament 8, from the shooting tube. This electron beam is focused and accelerated by grids g 4 to g 7 .
  • Coils not shown, provide the concentration and deflection of the beam.
  • FIG. 2 represents the diagram of an embodiment of a target according to the invention.
  • This target consists of a plate of optical fibers, 2 to 5 mm in length for example.
  • each optical fiber of the wafer has a blind hole which is obtained by eliminating, over a depth of 5 ⁇ m for example, the core of the fibers 12, without touching their coating 13. This can, for example, to be obtained by selective chemical attack on the two glasses constituting the core and the coating. There are thus obtained blind holes 5 ⁇ m deep, 5 ⁇ m in diameter, for example, and which are separated by walls of 2 ⁇ m for example.
  • a layer of luminescent material L 2 in grains, of high light output r 2 , is first deposited, then a barrier layer 14 and another layer of luminescent material L 1 , also in grains , but of low light output r 1 .
  • a thin metallic layer 15 is generally aluminum, evaporated under vacuum, with an appropriate incidence.
  • a thin metallic layer 151a layer L 1 is also covered.
  • the IIR comprises means, it is a manual or automatic switching device, which make it possible to subject the electron beam coming from its photocathode to two equal acceleration voltages, V 1 and V 2 , equal for example at 10 KV and 30 KV.
  • the thickness of the luminescent materials L 1 , L 2 and of the barrier layer 14 of FIG. 3 so that only the luminescent material L 1 of lower light output is excited by the electron beam subjected. at the lowest acceleration voltage V 1 , and so that the luminescent material L 2 with the highest light output is mainly excited by the electron beam subjected to the highest acceleration voltage V 2 .
  • FIG. 4 represents the variations in luminescence L as a function of the acceleration voltage for the materials Li and Lz.
  • the current density of the incident beam being constant, the luminance increases with the acceleration voltage from a threshold value V 01 for L 1 , V 02 for L 2 and the growth is faster for L 2 than for L 1 .
  • this beam is subjected to the lowest acceleration voltage V i , part, 50% for example, of the beam electrons does not exceed the layer L 1 and the other 50% do not exceed the barrier layer.
  • the excitation of the L 1 layer produces light, in a relatively small amount because of the low light output of this layer.
  • the outer surface of the layer L 1 and the walls of each blind hole being covered with the thin metallic layer 15 the light emitted by the layer L 1 of each fiber propagates along the fiber towards the face f 2 of the target 7 There is no light scattering and the same resolution is maintained as that of the fiber board.
  • the beam is subjected to the highest acceleration voltage V 2 , a part 15% for example, of the electrons of the beam does not exceed the layer L 1 , another part, 35% for example, does not exceed the layer- barrier and the rest excites the L 2 layer of high light output.
  • the luminescent material in grains L 1 which emits red light can consist for example of yttrium oxysulfide doped with europium or yttrium oxide doped with europium, with a particle size of less than 1 ⁇ m.
  • the luminescent material in grains L 2 which emits green light can consist, for example, of zinc cadmium sulfide doped with silver, with a particle size of less than 2 ⁇ m.
  • the L 1 layer is a monolayer with a thickness of less than 1 ⁇ m and the L 2 layer has a thickness of 4 ⁇ m for example.
  • FIG. 5 shows the variations in the transmission coefficient T of such an optical filter adapted as a function of the wavelength ⁇ .
  • the light emitted by the luminescent materials L 1 and L 2 propagates along the optical fibers to the opposite face f 2 of the target 7, the structure of which will be examined in FIG. 2.
  • the face f 2 of the target 7 is covered with a thin transparent conductive layer 9, which is obtained by evaporation under vacuum.
  • This layer can consist of tin oxide. SnO 2 , indium oxide In 2 O 3 , cadmium oxide Cd 0 3 , manganese oxide Mn 0, or mixtures of these oxides.
  • a conventional photosensitive target 11 of the shooting tube is deposited. It can be a continuous photoconductive layer or reverse polarized diodes.
  • This photoconductive layer can consist of antimony trisulfide, amorphous selenium, an amorphous compound of selenium tellurium, sulfur and arsenic, or also a layer of lead oxide.
  • This target is read line after line by the electron beam from the shooting tube.
  • the face f 2 of the wafer can, like the face f 1 , include blind holes filled with the three layers 9,10,11.
  • Figures 6, 7 and 8 show other embodiments of the face f 1 of the target.
  • the target consists of a wafer of optical fibers.
  • each fiber has a blind hole.
  • a layer of luminescent material L 2 in grains, of high luminous efficiency r 2 , is first deposited, then an evaporated layer Li of luminescent material, of low luminous efficiency r 1 , is deposited.
  • the evaporated layer L 1 can be chosen so that there is no need for a barrier layer interposed between the layers L 1 and L 2 , and that the lowest acceleration voltage V 1 causes excitation only layer L 1 and the highest acceleration voltage V 2 causes excitation of layer L 2 .
  • the evaporated layer L 1 can also be chosen to have a sufficiently low light output to obtain a gain which is multiplied by approximately 100 when going from V 1 to V 2 and without the need for an adapted optical filter.
  • the side walls of the blind holes and the external surface of the layer L 1 are covered with a thin metallic layer 15.
  • FIG. 7 represents an embodiment of the face f 1 of the target in which the surface of the wafer is covered with two evaporated layers L 1 and L 2 of luminescent material, with different light yields.
  • a barrier layer 14, also obtained by vacuum evaporation, can be if necessary interposed between the layers L 1 and L 2 .
  • a thin metal layer 15 covers the external surface of the layer L 1 of low light output.
  • the core 12 of the fibers protrudes from the surface of the wafer. This can, for example, be obtained by selective chemical attack of the two glasses constituting the core and the coating, as was the case for obtaining the blind holes of FIGS. 3 and 6, but there, it is the coating of fibers which is eliminated.
  • two evaporated layers L 1 and L 2 of luminescent material with different light yields are deposited on the surface of each core.
  • a thin metal layer 15 covers the layer L 1 and an evaporated barrier layer can be used if necessary.
  • the Li layer may consist of yttrium oxide or oxysulfide doped with europium and the L 2 layer may consist of yttrium oxysulfide doped with terbium. These two layers are deposited in a conventional manner by electron gun.
  • the target can be formed, no longer by a wafer of optical fibers, but by a semiconductor substrate, made of silicon, for example.
  • the silicon surface is then covered with two layers L 1 and L 2 which are preferably evaporated layers of luminescent material and not of luminescent grain material, so as to improve the resolution.
  • two layers of luminescent materials are no longer used, superimposed and possibly separated by a barrier layer.
  • Two types of luminescent grain materials are used, with different light output, but the grains of the two materials are mixed and the grains of one of the materials are covered with a barrier layer.
  • Figures 9 and 10 show two embodiments of an I.I.R. with video output comprising a target according to the invention.
  • the I.I.R. 20 and the picture tube 21 are located in two separate vacuum chambers.
  • the IIR tube comprises a target 7 such as that which is represented in FIG. 2, which consists of a wafer of optical fibers whose faces fi and f 2 are covered with several layers L 1 , L 2 , 15 and 9,10,11.
  • the enclosure of the shooting tube is fixed on that of the I.I.R using a flange 22, in pyroceram sealing for example.
  • This embodiment of the IIR avoids subjecting the high temperatures shooting tube necessitated for the realization of IIR. In addition, you can test the operation of the IIR before adapting the shooting tube.
  • the I.I.R. 20 and the shooting tube 21 are coupled by two separate optical fiber plates 22 and 23.
  • the plate 22 of the IIR carries on its left face f 1 the layers L i , L 2 and 15 as shown, for example, in Figures 3 and 6 to 8 and the plate 23 of the shooting tube carries on its right face f 2 the layers 9, 10, 11.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Measurement Of Radiation (AREA)
EP82400460A 1981-03-27 1982-03-12 Cible de tube intensificateur d'image et tube intensificateur d'image à sortie vidéo muni d'une telle cible Expired EP0062553B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8106187A FR2502842A1 (fr) 1981-03-27 1981-03-27 Cible de tube intensificateur d'image et tube intensificateur d'image a sortie video muni d'une telle cible
FR8106187 1981-03-27

Publications (2)

Publication Number Publication Date
EP0062553A1 EP0062553A1 (fr) 1982-10-13
EP0062553B1 true EP0062553B1 (fr) 1985-01-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP82400460A Expired EP0062553B1 (fr) 1981-03-27 1982-03-12 Cible de tube intensificateur d'image et tube intensificateur d'image à sortie vidéo muni d'une telle cible

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Country Link
US (1) US4647811A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
EP (1) EP0062553B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
JP (1) JPS57174842A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE3262002D1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
FR (1) FR2502842A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS595549A (ja) * 1982-07-02 1984-01-12 Toshiba Corp 防射線像増強管装置
JPS59201349A (ja) * 1983-04-28 1984-11-14 Toshiba Corp 螢光スクリ−ン及びその製造方法
FR2600177B1 (fr) * 1986-06-13 1988-08-19 Thomson Csf Procede de fabrication d'un intensificateur d'images radiologiques et intensificateur d'images radiologiques ainsi obtenu
JPH10172458A (ja) * 1996-12-10 1998-06-26 Hamamatsu Photonics Kk イメージインテンシファイア
JP2002505794A (ja) * 1997-06-13 2002-02-19 ガタン・インコーポレーテッド 電子顕微鏡の影像検出器の解像度を改良しノイズを低減する方法及び装置
WO2003083890A1 (fr) * 2002-03-28 2003-10-09 Kabushiki Kaisha Toshiba Tube amplificateur d'image radiologique, appareil equipe de ce tube et appareil radiologique
RU2326464C1 (ru) * 2007-03-19 2008-06-10 Вера Митрофановна Жилкина Электронно-оптический преобразователь
EP3043336B1 (en) * 2015-01-08 2021-06-23 Nokia Technologies Oy A light conversion element

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3237039A (en) * 1961-04-17 1966-02-22 Litton Prec Products Inc Cathode ray tube using fiber optics faceplate
US3243642A (en) * 1962-10-30 1966-03-29 Radames K H Gebel Image intensifier
US3522367A (en) * 1967-03-10 1970-07-28 Ncr Co Optical information display system
US3712986A (en) * 1969-04-03 1973-01-23 Westinghouse Electric Corp Electron imaging device utilizing a fiber optic input window
US3887724A (en) * 1972-11-22 1975-06-03 Us Army Method of making high contrast fiber optic phosphor screen
US4029965A (en) * 1975-02-18 1977-06-14 North American Philips Corporation Variable gain X-ray image intensifier tube
FR2356266A1 (fr) * 1976-06-25 1978-01-20 Thomson Csf Ecran de couleur a haute luminance pour tubes a rayons cathodiques, son procede de fabrication et tube cathodique incorporant un tel ecran
FR2445613A1 (fr) * 1978-12-29 1980-07-25 Thomson Csf Tube intensificateur d'image radiologique et chaine de radiologie incorporant un tel tube
US4264408A (en) * 1979-06-13 1981-04-28 International Telephone And Telegraph Corporation Methods for applying phosphors particularly adapted for intagliated phosphor screens

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
THOMSON-CSF CATALOGUE GTE 021 (Aout 1972), p. 15-17 *

Also Published As

Publication number Publication date
JPS57174842A (en) 1982-10-27
FR2502842B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1983-04-29
JPH0341935B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1991-06-25
FR2502842A1 (fr) 1982-10-01
DE3262002D1 (en) 1985-03-07
EP0062553A1 (fr) 1982-10-13
US4647811A (en) 1987-03-03

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