US3853374A - Method for the manufacture of photoelectron multipliers - Google Patents

Method for the manufacture of photoelectron multipliers Download PDF

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Publication number
US3853374A
US3853374A US00291281A US29128172A US3853374A US 3853374 A US3853374 A US 3853374A US 00291281 A US00291281 A US 00291281A US 29128172 A US29128172 A US 29128172A US 3853374 A US3853374 A US 3853374A
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United States
Prior art keywords
bulb
vessel
window
photosensitive layer
tube
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Expired - Lifetime
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US00291281A
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English (en)
Inventor
G Flasche
W Tretner
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Robert Bosch Fernsehanlagen GmbH
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Robert Bosch Fernsehanlagen GmbH
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Filing date
Publication date
Priority claimed from DE19712148809 external-priority patent/DE2148809C3/de
Application filed by Robert Bosch Fernsehanlagen GmbH filed Critical Robert Bosch Fernsehanlagen GmbH
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Publication of US3853374A publication Critical patent/US3853374A/en
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Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers

Definitions

  • the usual photocathode consists of a multi-component layer in which antimony or bismuth and one or more alkalis are present.
  • the photocathode support usually is a flat disc.
  • the photosensitive surface is very sensitive to extraneous gases and to overheating, e.g., in the sealing-in process, so that in the conventional manufacture of photocells,
  • the dynode structure was mounted on a glass stem, introduced into the bulb and the stem fused to the bulb. Then a metal layer was precipitated upon the front plate and an alkali-containing gas was introduced or developed which combined with the metal layer applied to the front plate so as to form an alloy.
  • This procedure is relatively complicated and is ill-suited to conveyer-line production. The quality of the cathode is adversely affected by gasses, released when the exhaust tube is tipped off.
  • the bulb and photocathode are joined and the bulb is sealed without glass fusion.
  • the photocathode is placed in a secondary chamber of a common vacuum vessel which can be divided by diaphragms.
  • the multiplier with its tube casing is placed in another section of the vacuum casing.
  • the bulb is provid'ed,-at its open edge, with a layer of indium.
  • alkali vapor is developed in the secondary chamber of the vacuum vessel and thereby the photocathode is shaped.
  • the photocathode is brought, by means of a manipulator, into the main chamber wherein the bulb section with the multiplier electrodes has been placed.
  • This bulb section is heated to such an extent that the metallic indium edge melts.
  • the photocathode support with the photocathode is placed upon the tube edge and the liquid indium produces the hermetic joint of the two parts.
  • cathodes, shielding electrodes, multiplier dynodes with the tube bulb section holding them, each in a closed vessel, each of the two vessels being provided with a crack-off groove; then opening both vessels in a common evacuated vessel by blasting, placing the photocathode support and the bulb section opposite each other by movable gripping devices, and sealing them hermetically to each other by pressure effect, e.g., by pressing an indium ring between the seam of the two tube sections.
  • pressure effect e.g., by pressing an indium ring between the seam of the two tube sections.
  • only the tube section that supports the. photocathode is moved by means of a gripping device and placed opposite the tube bulb section and finally closely thereto.
  • the photocathode, as well as the other electrodes of the tube can be processed under optimum conditions in separate vessels and be manufactured on a large scale, e.g., by mechanical means.
  • the vessels can be tested and stored. They are cracked open only at the proper time in the vacuum vessel unjoining the two vessels. From the photocell vessel, the front plate with the photocathode is removed and finally hermetically sealed to an edge of the other vessel by means of a cold-pressing process. This requires that the manufacture of the finished tube can in each case be carried out upon order,
  • the element to be connected to the photocathode may be, e.g., an electron multiplier, an electron-beam tube or an image converter.
  • the method is being employed, it is useful to fill the vacuum vessel joining the two vessels, before the cracking open, with alkali gases of low vapor pressure, so that the photocathode, when its vessel is opened, is exposed to an atmosphere changed as little as possible.
  • a further advantage of this method consists in that only such photocathodes are used for manufacturing the tubes which present a sufficient sensitivity.
  • the two sections to be joined may be rough-ground at the edges provided for the connection, so that hermetic sealing can be accomplished by the pressing process.
  • FIG. 1 is a schematic cross-sectional view of the auxiliary vessel for processing the photosensitive layer.
  • FIG. 2 is a schematic cross-sectional view of the apparatus during the step of receiving the photocathode from the vessel of FIG. 1.
  • FIG. 3 is a schematic cross-sectional view of an auxiliary device for removal of the photocathode.
  • FIG. 4 is a schematic cross-sectional view of an auxiliary vessel with the bulb section that contains the multiplier electrodes, after the blasting-open.
  • FIG. 5 is a schematic view of two evacuated vessels being opened in a third evacuated vessel to allow assembly of contents.
  • FIG. 6 is a schematic view of two evacuated vessels being opened in a third evacuated vessel to allow assembly of a multipart tube.
  • an auxilary vessel 1 contains a flat disc 2 for holding the photcathode and the necessary evaporation devices 4, 5 for producing precipitations upon the flat disc.
  • An antimony evaporator 4 and alkali channels 5 are fastened to support element 3 and are provided with connections to sealing wires 6, 7, etc. which supply current for heating the evaporation elements. Further pins (not shown) may serve to measure the photoelectric current during and after the processing.
  • the vessel is also provided with a crack-off groove in which a heating wire may be inserted whose electric heating opens bulb l at groove 8.
  • the cell of FIG. 1 is, after the usual complete processing first stored to observe possible aging processes.
  • the best of the stored cells may be selected for bulbs of top quality.
  • the other electrodes are mountedand properly processed.
  • the cell according to FIG. 1 is introduced into a bell jar 20 (FIG. 5) together with the auxiliary vessel 16 containing the multiplier electrodes of FIG. 4.
  • a good vacuum has been achieved in the bell jar, which may, in addition, be gettered by the introduction of alkali vapor, cells 1 and 16 are cracked open at the cracking grooves 8 and 17.
  • FIGS. 2 and 3 The process for the removal of the photocathode from auxiliary vessel 1 is explained by means of FIGS. 2 and 3.
  • FIG. 3 shows the gripping device 11 which abuts below a clamping ring 9' fastened to the photocahtode support.
  • a multiplier cell 12 with multiplier electrodes 13 has been opened by blasting open auxiliary vessel 16 at a cracking groove 17, in which process a suitable gripping device remove the upper section 16".
  • a multiplier vessel 12 is located in a support vessel 15, which is provided with holes for holding socket pins 14. Furthermore, this support vessel contains strong edges 18 which serve as abutment surfaces in the subsequent sealing of the vessel by pressing an indium ring.
  • the bottom portion 16' thereof is made of kovar.
  • a photocathode 9 is then mounted, by means of gripping device 11, opposite to the edge 12 of multiplier 12, and an indium ring is inserted between edges 17 of vessel 12 and the edge 9" of the photocathode 9.
  • photocathode 9 is pressed against vessel 12 and abutment surface l7, 18.
  • Edge 12' of the multiplier bulb 12 may be surface-ground for the purpose of safe connection to the front plate by means of indium.
  • Material capable of cold pressing other than indium may also be employed for the sealing.
  • the invention is not restricted to the employment of a front plate of glass. Materials with a coefficient of expansion very different from that of glass can also be employed.
  • the bell jar can be opened and the finished tube can be removed from the bell jar.
  • the finished tube may also be removed from the bell jar through a gate and at the same time a new pair of auxiliary vessels 1 or 16 may be introduced into the bell jar through another gate, whereupon the manu-. facture of the next specimen begins.
  • the sensitivity of the photoactive layer is substantially damaged by residual gases of oxygen or hydrogen which impair the oxidation state of the lead oxide.
  • the photosensitive layer is produced in a container and is transferred by a transfer process to the tube bulb likwise ready in the container, the residual gases produced in all vaporization or evaporation processes are harmful to the photosensitive layer.
  • the photosensitive layer is produced on a window in a closed auxilary vessl. The beam system of the plumbicon with the anode and other electrodes is likwise, during preparatory operation, degassed in a closed auxiliary vessel and the thermal cathode is processed.
  • the material is precipitated in one of the auxiliary vessels upon the window according to a well controlled process of evaporation for various metals, e.g., antimony, potassium, sodium, and cesium, in which process the cell can be conveniently controlled with respect to maximum photosensitivity.
  • various metals e.g., antimony, potassium, sodium, and cesium
  • auxiliary vessel it is degassed by preheating to such an extent that it later yields no vapors or other gases at all and presents optimum insulation. Then it is only necessary to crack open the two auxiliary vessels in a well evacuated container, to transfer the window with the photocathode to the aperture of the image converter vessel where, with insertion of an indium ring, it is pressed together therewith in such a manner that a hermetic seal is achieved. Again such hermetic seal can be readily assured by a polishing pretreatment of the surfaces to be joined.
  • a tube has to be constructed whose target is very sensitive to the conditions of the manufacture of the photocathode as well as of the thermal cathode and requires for manufacture thereof a vacuum practically free of residual gas.
  • the photocathode possibly with a special window, being provided in the first, and the bulb or the cathode ray tube with all electrodes, but without the target, being provided in the second, andthe target itself in the third.
  • Each of the three system can be manufactured only under optimum conditions. Their joining takes place in the container, after the auxiliary vessels are cracked open by means of two rings of ductile metal, e.g., indium.
  • the method also has the advantage of being readily adaptable to the most varied tasks, since entirely different tube parts can be joined in the same container after the exchange of inserts.
  • the damage done to parts is the smaller a) the shorter the duration of staying in the container, and b) the better vacuum.
  • the two values are mutually exchanageable, i.e., the poorer the vacuum, the less time must pass between the opening of the auxiliary vessels (removal of the window, transfer to the tube bulb) and closure of the tube bulb.
  • the most detrimental water vapor can be removed by a cooling finger which extends into the container and is filled with liquid air.
  • Method for manufacturing an electron discharge tube comprising a bulb which includes a photosensitive layer for detecting radiation in a certain band, which radiation enters the tube through a window, which window is permeable to radiation of that band, and which bulb further includes other electrode structure functioning in cooperation with the photosensitive layer for operation as an electron discharge tube, comprising the steps of:
  • sealing step comprises pressing a ductile, conductive material into a gap left between the window and the prepared opening.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US00291281A 1971-09-30 1972-09-22 Method for the manufacture of photoelectron multipliers Expired - Lifetime US3853374A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712148809 DE2148809C3 (de) 1971-09-30 Verfahren zum Herstellen von Elektronenröhren

Publications (1)

Publication Number Publication Date
US3853374A true US3853374A (en) 1974-12-10

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US00291281A Expired - Lifetime US3853374A (en) 1971-09-30 1972-09-22 Method for the manufacture of photoelectron multipliers

Country Status (4)

Country Link
US (1) US3853374A (https=)
JP (1) JPS4862375A (https=)
FR (1) FR2154657B3 (https=)
NL (1) NL7213217A (https=)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005920A (en) * 1975-07-09 1977-02-01 International Telephone And Telegraph Corporation Vacuum-tight metal-to-metal seal
US4030789A (en) * 1974-06-14 1977-06-21 U.S. Philips Corporation Method of manufacturing an electric discharge tube
US4052115A (en) * 1974-08-02 1977-10-04 U.S. Philips Corporation Device for manufacturing electron tube having a radiation-sensitive layer
US4286833A (en) * 1978-08-02 1981-09-01 The United States Of America As Represented By The Secretary Of The Army Method and apparatus to fabricate image intensifier tubes
US4309066A (en) * 1978-08-02 1982-01-05 The United States Of America As Represented By The Secretary Of The Army Method and apparatus to fabricate image intensifier tubes
US4799912A (en) * 1986-02-12 1989-01-24 Tungsram Reenytarsasag Method and apparatus for producing discharge tubes for sodium vapor lamps
US5369267A (en) * 1993-05-18 1994-11-29 Intevac, Inc. Microchannel image intensifier tube with novel sealing feature

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334955A (en) * 1965-06-03 1967-08-08 Itt Method and apparatus for making vacuum tubes

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334955A (en) * 1965-06-03 1967-08-08 Itt Method and apparatus for making vacuum tubes

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4030789A (en) * 1974-06-14 1977-06-21 U.S. Philips Corporation Method of manufacturing an electric discharge tube
US4052115A (en) * 1974-08-02 1977-10-04 U.S. Philips Corporation Device for manufacturing electron tube having a radiation-sensitive layer
US4005920A (en) * 1975-07-09 1977-02-01 International Telephone And Telegraph Corporation Vacuum-tight metal-to-metal seal
US4286833A (en) * 1978-08-02 1981-09-01 The United States Of America As Represented By The Secretary Of The Army Method and apparatus to fabricate image intensifier tubes
US4309066A (en) * 1978-08-02 1982-01-05 The United States Of America As Represented By The Secretary Of The Army Method and apparatus to fabricate image intensifier tubes
US4799912A (en) * 1986-02-12 1989-01-24 Tungsram Reenytarsasag Method and apparatus for producing discharge tubes for sodium vapor lamps
US5369267A (en) * 1993-05-18 1994-11-29 Intevac, Inc. Microchannel image intensifier tube with novel sealing feature

Also Published As

Publication number Publication date
DE2148809A1 (de) 1973-04-12
NL7213217A (https=) 1973-04-03
DE2148809B2 (de) 1976-12-23
JPS4862375A (https=) 1973-08-31
FR2154657A1 (https=) 1973-05-11
FR2154657B3 (https=) 1975-10-17

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