US3095251A - Manufacture of cascade image amplifiers - Google Patents

Manufacture of cascade image amplifiers Download PDF

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Publication number
US3095251A
US3095251A US2648A US264860A US3095251A US 3095251 A US3095251 A US 3095251A US 2648 A US2648 A US 2648A US 264860 A US264860 A US 264860A US 3095251 A US3095251 A US 3095251A
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US
United States
Prior art keywords
envelope
membranes
cathodes
cathode
photo
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
US2648A
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English (en)
Inventor
Slark Norman Arthur
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.)
Teledyne UK Ltd
Original Assignee
English Electric Valve Co Ltd
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
Priority to GB10335/59A priority Critical patent/GB871206A/en
Priority claimed from GB10335/59A external-priority patent/GB871206A/en
Application filed by English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
Priority to US94904A priority patent/US3055725A/en
Application granted granted Critical
Publication of US3095251A publication Critical patent/US3095251A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31D—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER, NOT PROVIDED FOR IN SUBCLASSES B31B OR B31C
    • B31D1/00—Multiple-step processes for making flat articles ; Making flat articles
    • B31D1/0031—Multiple-step processes for making flat articles ; Making flat articles the articles being paper nettings, e.g. by slitting and expanding webs or sheets
    • 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
    • H01J31/508—Multistage converters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/12—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel

Definitions

  • This invention relates to the manufacture of cascade image amplifiers, that is to say to image amplifiers Wherein an optical image to be amplified falls upon a photocathode the electrons from which are accelerated and focussed upon a fluorescent screen to form thereon a stronger optical image the light from which produces photo-emission from another photo-cathode which in turn emits electrons which are accelerated and focussed upon a further fluorescent screen where a still stronger optical image is formed to produce light to activate still another photo-cathode and so on through a desired cascade of image amplifying stages, each consisting of a photo-cathode and associated fluorescent screen, until an image of desired intensity is obtained on a final fluorescent screen.
  • FIG. 1 of the accompanying drawings shows schematically a typical known cascade image amplifier of the so-called sandwich type.
  • a photo-electric cathode C Deposited on the inside of one transparent end wall A of the envelope B of the tube is a photo-electric cathode C on which an optical image of a subject D (represented as an arrow) is focussed by means of a suitable lens system represented by a lens E.
  • Electrons emitted from the cathode C are accelerated and focussed by uniform electric and magnetic fields (generated by means not shown) on a fluorescent layer F on a thin transparent membrane G extending across the tube envelope.
  • a photo-cathode H On the other side of the membrane G is a photo-cathode H.
  • the applied electrical and magnetic fields are such as to cause the photo-electrons emitted from the cathode C to produce a stronger reproduction of the original optical image on the fluorescent screen F, the light from which causes photo-emission from the cathode H to occur and produce a still stronger optical image on the fluorescent screen P which in turn causes photo-emission from the cathode H to produce a still stronger image on the fluorescent screen F and so on until a bright image is produced on the final screen K.
  • the present invention seeks to overcome the foregoing defects and to provide methods of manufacture which will result in tubes having cathodes of practically uniformly good quality, and which can be made relatively small and compact, with only small spacing between the successive membranes, and with only small dark current. Indeed, it may be possible to employ the present invention to produce satisfactory tubes with the membranes so close togetherspaced by only a few millimetresthat eflective focusing can be obtained without any applied magnetic focusing fields at all.
  • a method of manufacturing a cascade image amplifier includes the steps of mounting a plurality of separate membranes on a carrier member in an evacuated space, mounting parts of the envelope while still in said evacuated space, bringing the separated parts of the envelope together and sealing them to one another to produce a hermetically sealed closed envelope with the processed cathodes in position inside it, and
  • the membranes are processed one at a time, While still on the carrier member, by being brought in turn into a heat treating oven mounted in the evacuated space.
  • the carrier member is a movable member adapted to carry the membrane in such positions thereon that, on moving said member, said membranes are moved through a path which passes through the heat treating oven and through a space adjacent one of the separated par-ts of the envelope, said membranes being lightly held in said positions so that, when a membrane has been brought into said space adjacent one of the separated parts of the envelope, it can be readily transferred from its position in said carrier member to a position in said one envelope part.
  • said movable carrier member is also adapted to carry the other separated part of the envelope,.said other pant of the envelope also being moved through a path which passes through the heat treating oven and through said space adjacent said one part of the envelope, said other part of the envelope being so held in position that it may be readily transferred from its position in said carrier member to a position adjacent and in contact with said one part of the envelope.
  • the image amplifier comprises transparent membranes each with a cathode on one side and a fluorescent layer on the other, and these membranes are mounted each across a short tubular mount which is lightly held in position on the carrier member and is adapted to fit into a I tubular member constituting one of the envelope parts.
  • an apparatus for carrying out a method of manufacture as hereinbefore set forth comprises an evacuatable chamber with a removable lid, a wheel mounted in said chamber and constituting a carrier member adapted lightly to hold a plurality of rotation of the wheel, said membranes and said closure portion carried thereby will pass in succession through said oven, means for rotating said'wheel fromoutside said chamber, means in said chamber for holding/a main envelope'portionwith'a space adjacent one end thereof said space being :so positioned that, on rotation of the Wheel, said membranes and said closure portion carried thereby will pass in succession through said space, a bellows structure for permitting the main envelope portions to be reciprocatedfrom outside the chamber to close and open said space and thereby transfer said membranes in turn and finally saidclosureiportion in said space to the inter-ior of the main envelope portion, and means permitting said envelope portions to be pressed tightly together to cold seal together metal seal members on the adjacent faces ofthe envelope portions.
  • FIG. Z'of the accompanying drawings illustrates one way of carrying out the invention and shows in schematic section a form of apparatus for practising: the method of the invention, FIG. 3 shows, so far as is necessary, a preferred modification of the apparatus of FIG. 2.
  • FIG. 2 there is an evacuatable chamber comprising a helmet-like lid member 1 of stainless steel and a base plate 2 having a hole 3 through which the chamber canbe pumped out via a pipe (not shown) fitted vacuum-tight tothe hole.
  • Thelid member 1 is bolted to the base 2 with interposed packing pieces 4to provide avacuum-tight joint.
  • Thelid member has a number of inspection windows in the top and sides one of these windows being shown at-S.
  • a tubular envelope carrier 6 in which can be fitted the, major portion 7 of the envelope of an image amplifier.
  • the part 6 is longitudinally movable between guides 8 and, is carried by a bellows structure 9 as shown to permit itto be moved longitudinally by meanssuch as a hand wheel 10' and screwed rod 11 from outside the chamber.
  • the envelope portion 7 is formed with an end copper or other suitable flange 7'.
  • the envelope portions 7 and 12 are spaced apart opposite one another in suchv a manner that by moving the part '6 endwise the flanges 7" and 12 can be brought into contact, said flanges being made of such material that they cold weld to one of any suitable type adapted to provide satisfactory heat treatment for processing a photo-cathode in accordance with known processing practice. 7 Within this oven are provided the necessaryevaporators or other -means;required to. deposit the required photo-cathode materials.
  • Membranes on which photo-cathodes are to be formed are carried on a rotatable conical wheel '15-which is rotatable on an axial shaft 16.
  • the wheel can be rotated from outside the chamber in any convenient manner, for
  • the wheel carries a ring of membranes on which photocathodes are to be formed.
  • Each photo-cathode is formed on one side of a transparent membrane :17 on the other, side of which is a fluorescent deposit except for the membrane on which the first photo-cathode is to be'formed, this membrane, :of course, not having-a fluorescent screen.
  • Each membrane is mounted across a short tubular glass mount '18 which-is lightly held to the wheel by a spring holder (not shown).
  • the mounts #18 are of suitable size
  • the completeenvelo'pe consists of the portion '7 and a closure portion 12 which is provided with'anend copper or similar flange 12 and is fitted into a fixed part 1 4. to fit into the envelope portion 7.
  • the oven 14*, the wheel 15, the holders for the mounts 18, and the parts holding the envelope portions 7 and 12, are in such mutual relationship that by rotating'the wheel 15, the mounts 18 will traverse a circular path which passes through the oven 14 and the space between'the envelope portions 7 and 12 when those portions are in the positions shown in' FIGURE 2.
  • the apparatus is used'as follows: The lid' is taken off the base 2. A number of mounts 18'each with its membrane having'a fluorescent screen on one side are' placed in the spring'holders on the wheel 15; an envelope portion 7 is put in position in the member 6 and an envelope closure portion 12 with an already prepared fluorescent screen on'the inside of its window, is placed in the" part 13. The lid 1 is then put into position on the base 2 and the chamber is pumped out and maintained in an evacuated condition. The wheel 15 is rotated through its magnetic drive to bring the'membranes carried byit in turn and one at a time into the oven 14 where each is heat treated and processed in accordance withiknown'practice to form a photo-cathode. When the photo-cathodes have been formed they can be examined for condition by.in-
  • the numberof' membranes carried by the wheel 15 is greater than the number of cathodes required in the complete-tube sothat the ones having the best photocathodes can be selected for putting in the tube and any bad ones rejected.
  • One of'the selected cathodes is then brought into position between the envelope portions 7 and 12' by rotating the wheel. operated to cause the'part 6, with the envelope portion 7:
  • Thewheel and screw mechanism 10-11 is now removed leaving thechamber still sealed.
  • a portable by draulic press (not shown) islowered over 'the'chamber. and pressure is applied between the parts 19 and 24 ⁇ which are formedto constitute thrust blocks for taking the pressure of the hydraulic press.
  • the wheel 15 is rotate-d'until a cut-out portion inthe rimthereof is brought between the envelope portions 7 and 12. These two portions are now brought into contact (the cut-out portion of the wheel 15 permitting this) by the hydraulic press and suflicient pressure is applied between them to cause a cold weld tooccur between the copper flanges 7" and V 12'.
  • the envelope is thus sealed. Vacuum is then released from the chamber, the lid 1 taken off the base 2 and the sealed envelope removed.
  • a getter may be conven--
  • the hand wheel '10' is then spirals so as to provide a uniform potential gradient between one membrane and the next when the image amplifier is in use.
  • external connectors (not shown) to the membranes and passing through the envelope portion 7 may be provided as required.
  • An advantage of the invention is that as a result of the individual treatment of individual photo-cathodes without affecting other photo-cathodes and without difficulties due to liberated caesium, it is possible to make a high gain image amplifier with the successive photo-cathodes spaced apart by much smaller amounts than are usually regarded as necessary. Indeed, it may be possible to adopt spacings as low as only a few millimetres each. While this obviously reduces the size of the amplifier, it also has the greater advantage that it enables focusing on the successive fluorescent screens to be obtained without the use of externally applied magnetic fields and the consequent elimination of solenoids or magnets for such fields not only reduces cost, but greatly reduces weight-an important matter for airborne apparatus in particular.
  • the first cathode of a cascade image amplifier tube shall be deposited direct on one of the end walls of the envelope and the final fluorescent screen deposited direct on the other end wall of said envelope.
  • a tube is represented in FIGURE 1 and the present invention can be used in the manufacture of such tube.
  • FIGURE 3 shows, so far as is necessary for an understanding thereof, a modification of the apparatus of FIGURE 2 which permits this method of manufacture to be done.
  • the portion 7 of the envelope (FIGURE 3) is provided with a preformed fluorescent screen 21 deposited on the inside of its end wall and the end closure portion 22 of the envelope is mounted in a holder on the wheel 15.
  • the spacer 22 does not carry a membrane and is placed in the tube 7 prior to its insertion in the tube 6.
  • the wheel is turned to bring the portion 22 opposite the portion 7.
  • the part 6 is again reciprocated and the closure portion 22 is transferred from its spring mount into the portion 7 where it is held by friction and the tube is sealed as already described.
  • the membrane mounts must be placed in their holders on the wheel the other way round so that, in the finished tube, each photo-cathode faces a fluorescent screen.
  • the wheel 15 carries more than one closure portion 22 and that one having the best photo-cathode is selected for use.
  • an external oven (not shown in the drawings) which is big enough to contain the whole evacuatable chamber of FIGURE 2 and which is raised to a temperature of several hundred degrees during the initial evacuation. This facilitates the obtaining of a high degree of cleanliness and enables a really high vacuum to be attained during processing. All the materials used in this case must be such as to Withstand this temperature and such as will outgas properly. It is also of advantage to provide getters in the evacuatable chamber and to fire them immediately before cathode processing is commenced, thereby removing residual gas traces which might otherwise harm the cathodes. traps in the pipe line from the evacuatable chamber to the vacuum pump, the upper of which can be baked at the same temperature as the chamber so as to aid in securing a high vacuum during cathode processing.
  • a method of manufacturing a cascade image amplifier including the steps of mounting a plurality of separate membranes on a carrier member in an evacuated space, mounting parts of the envelope of said amplifier in separated positions in said space, said parts being separated from said carrier member, depositing photo-cathode material on and heat treating said membranes to form photoelectric cathodes thereon while mounted on said carrier member in said space separated from said envelope parts, transferring desired processed cathodes from said carrier to predetermined positions in one of said envelope parts while still in said evacuated space, bringing the separated parts of the envelope together and cold sealing them to one another to produce a hermetically sealed closed envelope with the processed cathodes in position inside it, and releasing the vacuum and removing the sealed envelope from the space.
  • step of heat treating said membranes is accomplished on one membrane at a time while the membranes are on the carrier member by bringing the membranes in turn into a heat treating oven mounted in the evacuated space.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US2648A 1959-03-25 1960-01-15 Manufacture of cascade image amplifiers Expired - Lifetime US3095251A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB10335/59A GB871206A (en) 1960-01-15 1959-03-25 Improvements in or relating to the manufacture of cascade image amplifiers
US94904A US3055725A (en) 1960-01-15 1961-03-10 Apparatus for the manufacture of cascade image amplifiers

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Application Number Priority Date Filing Date Title
GB10335/59A GB871206A (en) 1960-01-15 1959-03-25 Improvements in or relating to the manufacture of cascade image amplifiers

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DE (1) DE1113044B (es)
FR (1) FR1247175A (es)
NL (1) NL248107A (es)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3752554A (en) * 1970-06-04 1973-08-14 J Thatcher Method of making a laser tube seal
US4094563A (en) * 1967-08-09 1978-06-13 Westinghouse Electric Corp. Method of fabricating an electron tube
US4175808A (en) * 1966-01-03 1979-11-27 Ni-Tec, Inc. Method and apparatus for producing electronic devices
US4186980A (en) * 1966-01-03 1980-02-05 Ni-Tec, Inc. Method and apparatus for constructing electronic devices

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2575756A (en) * 1949-10-21 1951-11-20 Gen Electric Exhaust machine
US2713532A (en) * 1951-04-30 1955-07-19 Eitel Mccullough Inc Electron tube and method of making the same
US2792271A (en) * 1950-08-16 1957-05-14 Gen Electric Method of making electric discharge device
US2837396A (en) * 1953-06-16 1958-06-03 Cons Electrodynamics Corp Process and apparatus for evacuating electronic tubes and the like

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2575756A (en) * 1949-10-21 1951-11-20 Gen Electric Exhaust machine
US2792271A (en) * 1950-08-16 1957-05-14 Gen Electric Method of making electric discharge device
US2713532A (en) * 1951-04-30 1955-07-19 Eitel Mccullough Inc Electron tube and method of making the same
US2837396A (en) * 1953-06-16 1958-06-03 Cons Electrodynamics Corp Process and apparatus for evacuating electronic tubes and the like

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4175808A (en) * 1966-01-03 1979-11-27 Ni-Tec, Inc. Method and apparatus for producing electronic devices
US4186980A (en) * 1966-01-03 1980-02-05 Ni-Tec, Inc. Method and apparatus for constructing electronic devices
US4094563A (en) * 1967-08-09 1978-06-13 Westinghouse Electric Corp. Method of fabricating an electron tube
US3752554A (en) * 1970-06-04 1973-08-14 J Thatcher Method of making a laser tube seal

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Publication number Publication date
NL248107A (es) 1964-03-10
FR1247175A (fr) 1960-10-17
DE1113044B (de) 1961-08-24

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