EP0553578B1 - Bildverstärkerröhre mit Intensitätsverteilungkompensation - Google Patents

Bildverstärkerröhre mit Intensitätsverteilungkompensation Download PDF

Info

Publication number
EP0553578B1
EP0553578B1 EP92400258A EP92400258A EP0553578B1 EP 0553578 B1 EP0553578 B1 EP 0553578B1 EP 92400258 A EP92400258 A EP 92400258A EP 92400258 A EP92400258 A EP 92400258A EP 0553578 B1 EP0553578 B1 EP 0553578B1
Authority
EP
European Patent Office
Prior art keywords
layer
photocathode
thickness
screen
scintillator
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
EP92400258A
Other languages
English (en)
French (fr)
Other versions
EP0553578A1 (de
Inventor
Yvan Raverdy
Gérard Vieux
François Chareyre
Alain Tranchant
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 Electron Devices SA
Original Assignee
Thomson Tubes Electroniques
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 Tubes Electroniques filed Critical Thomson Tubes Electroniques
Priority to DE1992610795 priority Critical patent/DE69210795T2/de
Publication of EP0553578A1 publication Critical patent/EP0553578A1/de
Application granted granted Critical
Publication of EP0553578B1 publication Critical patent/EP0553578B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • H01J29/38—Photoelectric screens; Charge-storage screens not using charge storage, e.g. photo-emissive screen, extended cathode
    • H01J29/385—Photocathodes comprising a layer which modified the wave length of impinging radiation

Definitions

  • the present invention relates to an X-ray image intensifier tube according to claim 1.
  • the radiological image intensifier tubes make it possible to transform a radiological image into a visible image, generally for medical observation.
  • These tubes are vacuum tubes comprising an input screen, an electronic optical system, and a screen for observing the visible image.
  • the input screen includes a scintillator which converts incident X photons into visible photons which then excite a photocathode, generally constituted by an alkaline antimonide, for example potassium antimonide doped with cesium.
  • a photocathode generally constituted by an alkaline antimonide, for example potassium antimonide doped with cesium.
  • the photocathode thus excited generates a flow of electrons.
  • the flow of electrons from the photocathode is then transmitted by the electronic optical system which focuses the electrons and directs them onto an observation screen made up of a phosphor which then emits visible light.
  • This light can then be processed, for example, by a television, cinema or photography system.
  • the input screen comprises an aluminum substrate covered by the scintillator, itself covered by an electrically conductive layer and transparent to the light coming from the scintillator, for example made of oxide of indium.
  • the photocathode is deposited on this transparent layer.
  • X-rays hit the entrance screen on the side of the aluminum substrate and pass through this substrate to reach the material constituting the scintillator.
  • the light photons produced by the scintillator are emitted a little in all directions.
  • a substance such as cesium iodide is generally chosen as scintillating material, which has the property of growing in the form of crystals perpendicular to the surface on which they are deposited.
  • the needle crystals thus deposited tend to guide the light perpendicular to the surface, which is favorable for good image resolution.
  • the surface of the input screen is not flat but curved; it can be parabolic or hyperbolic for large screens, or more generally in the form of a spherical cap for smaller screens.
  • the electronic density generated by the screen is not uniform.
  • the brightness curve represents the light intensity in each point of the diameter of the output screen.
  • this curve is not horizontal; it is generally in the form of an arc of a circle slightly flattened in the center; the brightness of the output screen is maximum towards the center but decreases markedly as one approaches the edges.
  • the reduction in gloss on the edges relative to the center is around 25%.
  • the brightness curve of the intensifier tube can be improved much more easily without affecting the thickness of the scintillator and without adding an optically absorbent layer, and by using rather some very specific properties of the thin transparent layer placed under the photocathode.
  • the photocathode is made of a chemically fairly unstable material which will react with the under layer on which it is deposited; this reaction will modify the emissive properties of the photocathode, and this to an extent related to the thickness of the under layer in the case where this thickness is very thin, that is to say in the case where it does not exceed not a few hundred nanometers.
  • the invention therefore proposes to place a very thin intermediate layer of radially variable thickness under the photocathode.
  • This layer is preferably transparent; it is preferably conductive; its thickness is preferably less than a few hundred angstroms; it is preferably made of indium oxide.
  • photocathodes potassium antimonide doped with cesium. These photocathodes are very reactive, especially during their deposition because of the high temperature prevailing in the depository. They are strongly reducing and react strongly with rather oxidizing substances.
  • the final brightness of the intensifier tube strongly depends on the thickness of the layer of indium oxide. The dependence is much stronger than that which results from the simple (negligible) optical absorption properties of this layer. This is why it is particularly advantageous to give a variable thickness radially to this layer in order to modify the gloss curve at will.
  • the order of magnitude of the thicknesses is preferably as follows: approximately 250 angstroms at the edges and 400 angstroms at the center.
  • FIG. 1 shows a conventional brightness curve of an image intensifier tube, taken along a diameter of the output screen: it represents the brightness of a line of dots of the image visible on the screen of output as a function of the distance of these points from the center of the screen, assuming uniform illumination of the input screen.
  • the illumination is a uniform beam of X-rays.
  • the general structure of a conventional radiological image intensifier is shown in Figure 2.
  • the vacuum tube enclosure contains an EE input screen at the front and an ES output screen at the rear. Electron beam focusing electrodes are provided in the enclosure.
  • the input screen is most often curved in parabolic or hyperbolic form, with a strong curvature, for reasons of electronic optics, that is to say to make possible a homogeneous focusing of the electrons on the screen of exit.
  • This curvature is one of the causes of the shape of the gloss profile of the tube.
  • the EE input screen is most often formed by a curved aluminum sheet 10, on which a scintillating layer 12 has been deposited (cesium iodide, several hundred micrometers thick) itself covered with a transparent conductive electrode 14 (most often made of indium oxide In2O3) then a photocathode 16 (for example made of potassium and cesium antimonide).
  • a scintillating layer 12 cesium iodide, several hundred micrometers thick
  • a transparent conductive electrode 14 most often made of indium oxide In2O3
  • a photocathode 16 for example made of potassium and cesium antimonide
  • the transparent conductive electrode (14) is intended to uniformly fix the potential of the photocathode.
  • an intermediate layer between the scintillator layer and the photocathode (and this layer may be the transparent conductive electrode 14 itself) be deposited with a thickness that is radially variable from the center to the edges, this intermediate layer being chosen from a material which modifies the emissive properties of the photocathode as a function of the thickness deposited.
  • the intermediate layer is quite simply the layer of indium oxide 14 serving as transparent conductive electrode under the photocathode.
  • the thickness varies radially. It is greater (thickness e1) in the center of the screen than at the edges (thickness e2), because it turns out that an increase in thickness of the layer 14 causes a reduction in gloss. We therefore compensate for the excessive curvature of the gloss profile of FIG. 1.
  • the thickness variation is in practice continuous from the center to the edges.
  • the deposit with variable thickness is carried out in a known manner by evaporation in the presence of a mask which rotates in front of the surface to be covered, the shape of the mask being defined as a function of the thickness profile to be obtained.
  • the thicknesses are a few hundred angstroms.
  • indium oxide In2O3 is possible.
  • Partially reduced indium oxide In x O y in thickness of the order of a few hundred angstroms may also be suitable.
  • the thickness variation can be of the same order of magnitude as for stoichiometric indium oxide.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

Claims (5)

  1. Bildverstärkerröhre für ein Röntgenbild mit einem Ausgangsschirm, der ein sichtbares Bild liefert, und einem Eingangsschirm, der eine Scintillatorschicht (12), eine Fotokathodenschicht (16) und eine dünne Zwischenschicht (14) trägt, die zwischen der Scintillatorschicht und der Fotokathodenschicht liegt, dadurch gekennzeichnet, daß die dünne Zwischenschicht transparent ist und durch Aufbringen eines Materials erhalten wird, das mit der Fotokathode während der Herstellungsphase reagieren kann, wobei die Dicke dieser Zwischenschicht in radialer Richtung in einem solchen Maße variabel gewählt wird, daß die Emissionseigenschaften der Fotokathode örtlich nach Maßgabe der Dicke dieser Schicht variieren.
  2. Röhre nach Anspruch 1, dadurch gekennzeichnet, daß die transparente Zwischenschicht eine leitende Schicht ist.
  3. Röhre nach einem der Ansprüche 1 und 2, dadurch gekennzeichnet, daß das Material ein Metalloxid, insbesondere stöchiometrisches Indiumoxid In₂O₃ oder teilweise reduziertes Indiumoxid InxOy ist und die Dicke in der Größenordnung von einigen hundert Å liegt.
  4. Röhre nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Dicke der Zwischenschicht im Zentrum größer als an den Rändern des Eingangsbildschirms ist.
  5. Röhre nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Fotokathode aus einem stark reduzierenden Material besteht und daß die Zwischenschicht aus einem eher oxidierenden Material besteht.
EP92400258A 1990-08-31 1992-01-31 Bildverstärkerröhre mit Intensitätsverteilungkompensation Expired - Lifetime EP0553578B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE1992610795 DE69210795T2 (de) 1992-01-31 1992-01-31 Bildverstärkerröhre mit Intensitätsverteilungkompensation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR9010870A FR2666447B1 (fr) 1990-08-31 1990-08-31 Tube intensificateur d'image avec compensation de courbe de brillance.

Publications (2)

Publication Number Publication Date
EP0553578A1 EP0553578A1 (de) 1993-08-04
EP0553578B1 true EP0553578B1 (de) 1996-05-15

Family

ID=9399992

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92400258A Expired - Lifetime EP0553578B1 (de) 1990-08-31 1992-01-31 Bildverstärkerröhre mit Intensitätsverteilungkompensation

Country Status (3)

Country Link
US (1) US5256870A (de)
EP (1) EP0553578B1 (de)
FR (1) FR2666447B1 (de)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5635720A (en) * 1995-10-03 1997-06-03 Gatan, Inc. Resolution-enhancement device for an optically-coupled image sensor for an electron microscope
FR2758002B1 (fr) * 1996-12-27 2004-07-02 Thomson Tubes Electroniques Systeme de visualisation avec ecran d'observation luminescent
IL120774A0 (en) * 1997-05-04 1997-09-30 Yeda Res & Dev Protection of photocathodes with thin films
FR2782388B1 (fr) 1998-08-11 2000-11-03 Trixell Sas Detecteur de rayonnement a l'etat solide a duree de vie accrue
US6700123B2 (en) * 2002-01-29 2004-03-02 K. W. Muth Company Object detection apparatus
US20040036973A1 (en) * 2002-06-01 2004-02-26 Giuseppe Iori Multi-layer interference filter having colored reflectance and substantially uniform transmittance and methods of manufacturing the same
CN104749604B (zh) * 2013-12-30 2018-06-01 同方威视技术股份有限公司 多技术融合闪烁探测器装置
GB2524778A (en) * 2014-04-02 2015-10-07 Univ Warwick Ultraviolet light detection

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3716713A (en) * 1969-01-09 1973-02-13 Varian Associates Input screen for image devices having reduced sensitivity in the cental region
US3706885A (en) * 1971-01-29 1972-12-19 Gen Electric Photocathode-phosphor imaging system for x-ray camera tubes
US3838273A (en) * 1972-05-30 1974-09-24 Gen Electric X-ray image intensifier input
NL8602629A (nl) * 1986-10-21 1988-05-16 Philips Nv Roentgenbeeldversterkerbuis met een scheidingslaag tussen de luminescentielaag en de photocathode.
NL8900040A (nl) * 1989-01-09 1990-08-01 Philips Nv Roentgenbeeldversterkerbuis met selectief filter.
JP2758206B2 (ja) * 1989-05-23 1998-05-28 株式会社東芝 Ｘ線イメージ管
FR2647955B1 (fr) * 1989-05-30 1991-08-16 Thomson Tubes Electroniques Ecran d'entree de tube intensificateur d'image radiologique

Also Published As

Publication number Publication date
FR2666447B1 (fr) 1996-08-14
EP0553578A1 (de) 1993-08-04
FR2666447A1 (fr) 1992-03-06
US5256870A (en) 1993-10-26

Similar Documents

Publication Publication Date Title
EP0554145B1 (de) Bildverstärkerröhre, insbesondere für Nahfokusröhre
EP0553578B1 (de) Bildverstärkerröhre mit Intensitätsverteilungkompensation
EP0559550B1 (de) Mikrokanalplatte-Bildverstärkerröhre, insbesondere geeignet für radiologische Bilder
EP0428667B1 (de) Eingangsschirm für eine röntgenbildverstärkerröhre
EP0325500B1 (de) Szintillator für einen Eingangsschirm einer Röntgenstrahl-Bildverstärkerröhre und sein Herstellungsverfahren
EP0403802B1 (de) Röntgenbildverstärker und Verfahren zur Herstellung des Eingangsschirmes
EP0540391B1 (de) Röntgenbildverstärkerröhre
EP0319080B1 (de) Röntgenstrahl-Bildverstärkerröhre
EP0125962B1 (de) Röntgenbildverstärker und dessen Anwendung bei rechnergestützter Röntgenaufnahmetechnik
EP0062553B1 (de) Treffelektrode für Bildverstärkerröhre und mit solcher Treffelektrode versehene Bildverstärkerröhre mit Video-Ausgang
EP0013241B1 (de) Röntgenbildverstärkerröhre mit Video-Ausgabe und radiologische Anordnung mit einer derartigen Röhre
FR2521781A1 (fr) Convertisseur d'images radiologiques
EP0412887B1 (de) Mit hohem Wirkungsgrad kathodolumineszenter Schirm für hochleuchtende Kathodenstrahlröhre
FR2545269A1 (fr) Ecran electroluminescent et son procede de fabrication
FR2479559A1 (fr) Procede de fabrication d'ecrans luminescents
EP0851455B1 (de) Röntgenbildverstärkerröhre
EP0143714B1 (de) Lumineszenter Schirm und Verfahren zur Herstellung desselben
EP0533538B1 (de) Bildverstärkerröhre mit Helligkeitskorrektur
JPH08306328A (ja) Ｘ線撮像管
EP0176422A1 (de) Bildaufnahmeröhre, Anordnung mit einer solchen Röhre und Verfahren zum Betrieb derselben
FR2491677A1 (fr) Multiplicateur d'electrons, procede de fabrication et tubes images comportant ledit multiplicateur
BE519239A (de)
EP0427842A1 (de) Kathodolumineszenter dünnschichtschirm für ein kathodenstrahlrohr mit hoher luminenz

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE GB NL

17P Request for examination filed

Effective date: 19930809

17Q First examination report despatched

Effective date: 19940325

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB NL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19960515

REF Corresponds to:

Ref document number: 69210795

Country of ref document: DE

Date of ref document: 19960620

GBV Gb: ep patent (uk) treated as always having been void in accordance with gb section 77(7)/1977 [no translation filed]

Effective date: 19960515

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20110117

Year of fee payment: 20

Ref country code: DE

Payment date: 20110126

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69210795

Country of ref document: DE

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69210795

Country of ref document: DE

REG Reference to a national code

Ref country code: NL

Ref legal event code: V4

Effective date: 20120131

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20120201