US3497759A - Image intensifiers - Google Patents

Image intensifiers Download PDF

Info

Publication number
US3497759A
US3497759A US729126A US3497759DA US3497759A US 3497759 A US3497759 A US 3497759A US 729126 A US729126 A US 729126A US 3497759D A US3497759D A US 3497759DA US 3497759 A US3497759 A US 3497759A
Authority
US
United States
Prior art keywords
channel
photo
channels
electrode
electrons
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
US729126A
Other languages
English (en)
Inventor
Brian William Manley
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.)
US Philips Corp
Original Assignee
US Philips Corp
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 US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3497759A publication Critical patent/US3497759A/en
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
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/24—Dynodes having potential gradient along their surfaces
    • 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
    • H01J31/506—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect
    • H01J31/507—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect using a large number of channels, e.g. microchannel plates

Definitions

  • This invention relates to electron multiplier and image intensifier devices. More particularly the invention relates to channel intensifier devices and to electronic tubes employing such devices.
  • a channel intensifier device is a secondary-emissive electron multiplier device which device comprises a resistive matrix in the form of a plate the major surfaces of which constitute the input and output faces of the matrix, a conductive layer on the input face of the matrix serving as an input electrode, a separate conductive layer on the output face of the matrix serving as an output electrode, and elongated channels each providing a passageway from one face of the assembly consisting of matrix and input and output electrodes to the other face of said assembly.
  • the distribution and cross-sections of the channels and the resistivity of the matrix are such that the resolution and electron multiplication characteristics of any one unit area of the device is sufiiciently similar to that of any other unit area for any imaging purposes envisaged.
  • an imaging tube or system If such a device is used in an imaging tube or system, the latter will be referred to for convenience as an image intensifier tube or system rather than as an image converter tube or system even in applications where the primary purpose is a change in the wavelength of the radiation of the image.
  • British patent specifications 1,064,073, 1,064,074 and 1,064,076 describe examples of a channel intensifier device used in conjunction with a photo-cathode spaced from the input electrode and with a suitable target, for example a luminescent screen so as to form an arrangement suitable for an image intensifier tube, for example for viewing scenes at low illumination.
  • the photo-emissive surface areas may substantially all be formed on the input electrode of the matrix and they may constitute an electrically continuous apertured layer, which can be represented as the layer P in FIG- URE 1 of the accompanying diagrammatic drawings.
  • An object O is shown imaged by an optical system on to the photo-cathode P. Photo-electrons are liberated simultaneously from all parts of the photo-cathode with varying local intensities dependent upon the image formed thereon. Secondary electrons emerging from channel intensifier device I are accelerated towards a luminescent screen S.
  • the channel intensifier device I is traversed by a regular array of channels.
  • the matrix of the device may be of glass and its input and output faces carry first and second conductive electrode layers E1-E2 respectively.
  • each of the channels that receives primary electrons at any given instant multiplication takes place and the necessary electric accelerating field is set up by connecting the electrodes El-EZ to a source shown schematically at B2.
  • a further accelerating field is provided by a source shown schematically as a unit B3 connected between E2 and a conductive coating (e.g. aluminum) associated with luminescent screen S.
  • Photo-electrons are emitted in a direction away from the matrix and input electrode E1 and such electrons require a field to turn them back towards the channels.
  • Means for producing such a field are represented diagrammatically by a source B1 applying a voltage between the input electrode E1 and a transparent electrode E0 formed e.g. on the envelope.
  • a source B1 applying a voltage between the input electrode E1 and a transparent electrode E0 formed e.g. on the envelope.
  • the photo-emissive surface areas is shown to be formed substantially entirely within the channels of the matrix.
  • the accelerating field set up by source B2 between electrodes El and E2 is clearly suflicient to accelerate the electrons in the channels without the need to have an electrode corresponding to E0 with its source B1.
  • the photo-emissive surface areas have been laid partly on the input electrode on the matrix and partly inside its channels.
  • a channel image intensifying device for electrons comprising a thin plate of glass of high electrical resistance or of a ditfe r ent kind of similar material, which plate is provided on the two major surfaces with an electrically conductive layer and with closely adjacent channels interconnecting the two surfaces and with a photo-electric cathode in contact with one of the two surfaces, the photo-electric cathode closes the passages at the entrances to the channels and is sufliciently permeable for rays of those wavelengths to which the photo-cathode material is sensitive.
  • the entrances to all the channels are closed by photoemissive areas, and the device can operate satisfactorily even if some parts of the input electrode are not quite in direct physical contact with the photo-emissive layer owing, say, to irregularities in said layer or in said electrode or to the presence of dust particles.
  • the invention also overcomes the aforesaid second problem which exists in previous arrangement of the proximity type in that electrons from each picture element on the photo-cathode are constrained to enter the appropriate channel, and this of course produces maximum definition for a given channel density or for a given total number of channels.
  • FIGURE 1 illustrates the prior art
  • FIGURE 2 represents schematically an image intensifier tube according to the invention
  • FIGURES 3 to 5 illustrate 3 embodiments of the invention
  • FIGURE 6 illustrates a modification of the invention
  • FIGURE 7 illustrates a method of manufacture
  • FIGURES 8 and 9 illustrate in a simplified manner the action of symmetrical and asymmetrical (i.e. tilted) lenses respectively
  • FIGURE 10 illustrates a further embodiment.
  • FIG. 1 In the generic representation of an imaging tube employing a channel-intensifier photo-cathode combination according to the present invention as shown in FIGURE 2 the input voltage supply B1 and the separate electrode E0 of FIG. 1 have been omitted. Though the photoemissive material has a degree of conductivity of its own the original input electrode E1 is retained as part of the channel intensifier device. Electrode E1 communicates its own potential to the photoemissive areas since they are in contact with it as explained above. Thus the photoemitter and input electrode can be indicated as being connected together to one end of the supply B2.
  • a continuous photo-emissive layer P is brought up to, and placed in contact with, the input electrode E1.
  • the parts of the photo-emissive layer which correspond to the electrode E1 perform no photo-emissive function in the device.
  • it may be the easiest and cheapest method of construction by depositing layer P on a glass plate W which may be the window of the envelope since the photo-emissive surface areas can be produced as a continuous layer before assembly.
  • the areas of the photo-emitter which correspond to the channels C are the operative areas and they emit photo-electrons directly into the channels. This permits the electrons to initiate their travel in the channels at a lower energy so that they can more easily be directed towards the channel walls at an early stage.
  • FIG- URES 4- and 5 This can be done in different ways and these alternative arrangements are illustrated in FIG- URES 4- and 5.
  • the input electrode E1 is extended some way into each channel entrance so as to create an electrostatic lens effect which deflects the electrons outwardly towards the channel Walls. This lens action will be described in greater detail later.
  • FIGURE 5 the channels are tilted so as to cause early collisions as shown schematically. It is possible to combine the configurations of FIGURES 4 and 5 (although this is not normally necessary) or the lenses themselves may be tilted as will be explained.
  • a modification of the present invention consists in omitting the input electrode E1 and relying solely on the conductivity of the photo-emissive areas to act as an input electrode. For this reason areas must, as in the arrangements of FIGS. 35, be joined together to form an electrically continuous layer which is connected to one of the supply terminals. An example of such an arrangement is shown in FIGURE 6.
  • the input electrode is regarded as constituted by the photo-emissive layer wherein the input electrode is no longer traversed by the passageways provided by the channels.
  • a special case of the FIGURE 6 type is the case in which the concerned photo-emissive and electrode material PE is a metal adapted to act as a photo-emitter at given wavelengths of input radiation, for example gold for an ultra-violet image intensifier.
  • a metallic layer must be thin enough to be partially transparent and this may unduly limit its current carrying capacity as compared with the arrangements of FIGURES 3 to 5 wherein the electrode E1 has apertures to pass radiation and therefore can be of any desired thickness.
  • a similar limitation may exist also when the layer PE of the arrangement of FIGURE 6 is of a material other than gold.
  • the electrode E1 can be formed on the matrix by known methods. If it is to be extended into the channels in accordance with FIGURE 4, it can be formed by evaporating a metal (e.g. chromium) at a suitable angle 5 as shown in FIG- URE 7, such evaporation (3) being effected from a source which is rotated round the axis of the matrix so as to cause uniform penetration the channel plate is itself rotated (or relative to a fixed source).
  • the chosen value of the angle 5 of evaporation determines the depth of the inward penetration d of the electrode material inside the channels 2. This forms both the input face layer 1 of the electrode and the extensions 4 of the electrode into the channels.
  • FIGURES 3 to 5 may be made by depositing the layer P on to a substrate plate W and assembling said plate against the electrode E1 of the channel device. This must be done with sufiicient accuracy to ensure that layer P is in contact with all or nearly all the parts of the electrode, and the two steps should be carried out in vacuo. Corresponding steps can be adopted for the case of FIGURE 6 but in this case the assembly can be carried out in air if the layer PE is of gold as previously described.
  • Electrons produced from the photocathode in response to light or other radiation must acquire so much energy that, when they strike the wall of a channel, the
  • secondary emission coefficient will be substantially greater than unity. This requires in practice collision energies which exceed 50 ev. It is also important, however, that electrons from the photocathode do not penetrate far into the channel before collision with the wall, since the length of channel available for the subsequent gain process will be inadequate. Usually a channel plate is separated from the photocathode by a small distance (between one and ten channel diameters), and the application of a potential difife rence exceeding 50 v. (between photocathode and channel plate input electrode) to ensure that photoelectrons enter a channel with sufficient energy to produce secondary electrons on collision with the wall of the channel.
  • the field strength in the channel plate is made different from that in the space between photocathode and channel plate.
  • a lens action is established at the channel entrance, which will be positive if the field strength in the channel plate is the higher, or negative if it is the lower.
  • the strength of this lens is to be adequate to ensure that electrons are directed to strike the wall in the early part of the channel, it is necessary that either the disparity in field strengths be very great, or the energy of the electron as it enters the lens be small, so that it is readily deflected.
  • the electric field within the channel plate is normally fixed by the gain required from the plate and its geometry, and there is little or no freedom to choose the field strength to suit electron-optical requirements.
  • either the field strength in the photocathode/channel-plate ga must be made very high (in which case field emission from the photocathode becomes a danger) or it must be made very low, in which case the electrons from the photocathode will spread before reaching the channel plate and resolution will be lost.
  • the degree of penetration of the electrode will influence the lens strength. As a limit case, no penetration will result in no lens action, and the photoelectrons will spread in straight paths from the photocathode. Deep penetration several channel diameters in extent will give strong curvature of the equipotentials and a strong lens action; however, many photoelectrons will drift to the wall in the electrode region without gaining any energy and so will be lost. The best compromise appears to lie with a penetration between A and 2 channel diameters in depth, preferably between /2 and one diameter. In this range a large fraction of the photoelectrons will gain sufficient energy (before collision) to produce secondary electrons, and few still pass far into the channel without collision.
  • FIG- URE 8 The lens action is shown diagrammatically in FIG- URE 8.
  • the electrode penetration forming the lens can be tilted according to FIGURE 9. This has the result of accelerating the electrodes preferentially to one side of the channel, and even a photoelectron emitted along the channel axis will collide with the wall.
  • Tilted electrode penetration i.e. tilted lenses
  • metal forming the input electrode typically Cr
  • skew penetration like that shown in FIGURE 9 can be obtained by omitting the rotation.
  • the effective photocathode area of any of the devices described can be increased by outwardly flaring or tapering the entrances to the channels so that their initial diameter is larger. This is illustrated schematically in FIG. 10.
  • the dimensions of the matrix may be approximately as follows:
  • the source B may produce about 1000 volts.
  • An electron multiplier comprising a thin plate of electrically insulating material, said plate having an electrically conducting layer on the two major faces and being provided wi.h a plurality of parallel closely adjacent narrow secondary emissive channels interconnecting the two major faces, and a photoelectric cathode contacting one of the two major faces, and closing the entrances to the channels and sufiiciently permeable to radiation of such wavelengths to which the photocathode material is sensitive to emit electrons in response to said radiation which enter said channels.
  • a device as claimed in claim 2 characterized in that between the photocathode and the plate surface a conductive layer is provided which extends into the channels.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US729126A 1967-05-15 1968-05-14 Image intensifiers Expired - Lifetime US3497759A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB22339/67A GB1154515A (en) 1967-05-15 1967-05-15 Improvements in or relating to Image Intensifiers

Publications (1)

Publication Number Publication Date
US3497759A true US3497759A (en) 1970-02-24

Family

ID=10177803

Family Applications (1)

Application Number Title Priority Date Filing Date
US729126A Expired - Lifetime US3497759A (en) 1967-05-15 1968-05-14 Image intensifiers

Country Status (7)

Country Link
US (1) US3497759A (xx)
AT (1) AT281142B (xx)
DE (1) DE1764236A1 (xx)
FR (1) FR1565868A (xx)
GB (1) GB1154515A (xx)
NL (1) NL6806736A (xx)
SE (1) SE339058B (xx)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3769539A (en) * 1969-02-24 1973-10-30 Bendix Corp Camera tube
US3863094A (en) * 1969-04-08 1975-01-28 Itt Image intensifier and method of making an electron multiplier therefor
US3870917A (en) * 1971-05-10 1975-03-11 Itt Discharge device including channel type electron multiplier having ion adsorptive layer
US3902240A (en) * 1972-11-22 1975-09-02 Us Army Integrated cathode and channel plate multiplier
US3939374A (en) * 1973-01-19 1976-02-17 U.S. Philips Corporation Electron multipliers having tapered channels
US3974411A (en) * 1970-09-20 1976-08-10 Rca Corporation Channel plate electron multiplier tube having reduced astigmatism
US4025813A (en) * 1974-02-13 1977-05-24 U.S. Philips Corporation Microchannel plate comprising microchannels curved on the output side
EP0131336A1 (en) * 1983-07-08 1985-01-16 Philips Electronics Uk Limited Cathode ray tube
EP0559550A1 (fr) * 1992-03-06 1993-09-08 Thomson Tubes Electroniques Tube intensificateur d'image, notamment radiologique, du type à galette de microcanaux

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1402549A (en) * 1971-12-23 1975-08-13 Mullard Ltd Electron multipliers
GB1434053A (en) * 1973-04-06 1976-04-28 Mullard Ltd Electron multipliers
GB1464863A (en) * 1973-05-21 1977-02-16 Agfa Gevaert Production of electrostatic images
GB2118358B (en) * 1982-04-05 1986-01-02 Philips Electronic Associated Channel plate electron multipliers
US4737013A (en) * 1986-11-03 1988-04-12 Litton Systems, Inc. Microchannel plate having an etch limiting barrier
WO1992016960A1 (en) * 1991-03-15 1992-10-01 Sovetsko-Amerikanskoe Sovmestnoe Predpriyatie Dialog Method and device for detection of radiation
CN108054075B (zh) * 2017-12-14 2024-05-14 中国科学院西安光学精密机械研究所 一种分幅变像管及分幅相机

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2942133A (en) * 1953-06-05 1960-06-21 Electrical & Musical Ind Ltd Electron multipliers
US3001098A (en) * 1954-03-17 1961-09-19 Westinghouse Electric Corp X-ray image intensifying device
US3374380A (en) * 1965-11-10 1968-03-19 Bendix Corp Apparatus for suppression of ion feedback in electron multipliers
US3407324A (en) * 1967-06-21 1968-10-22 Electro Mechanical Res Inc Electron multiplier comprising wafer having secondary-emissive channels

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2942133A (en) * 1953-06-05 1960-06-21 Electrical & Musical Ind Ltd Electron multipliers
US3001098A (en) * 1954-03-17 1961-09-19 Westinghouse Electric Corp X-ray image intensifying device
US3374380A (en) * 1965-11-10 1968-03-19 Bendix Corp Apparatus for suppression of ion feedback in electron multipliers
US3407324A (en) * 1967-06-21 1968-10-22 Electro Mechanical Res Inc Electron multiplier comprising wafer having secondary-emissive channels

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3769539A (en) * 1969-02-24 1973-10-30 Bendix Corp Camera tube
US3863094A (en) * 1969-04-08 1975-01-28 Itt Image intensifier and method of making an electron multiplier therefor
US3974411A (en) * 1970-09-20 1976-08-10 Rca Corporation Channel plate electron multiplier tube having reduced astigmatism
US3870917A (en) * 1971-05-10 1975-03-11 Itt Discharge device including channel type electron multiplier having ion adsorptive layer
US3902240A (en) * 1972-11-22 1975-09-02 Us Army Integrated cathode and channel plate multiplier
US3939374A (en) * 1973-01-19 1976-02-17 U.S. Philips Corporation Electron multipliers having tapered channels
US4025813A (en) * 1974-02-13 1977-05-24 U.S. Philips Corporation Microchannel plate comprising microchannels curved on the output side
EP0131336A1 (en) * 1983-07-08 1985-01-16 Philips Electronics Uk Limited Cathode ray tube
EP0559550A1 (fr) * 1992-03-06 1993-09-08 Thomson Tubes Electroniques Tube intensificateur d'image, notamment radiologique, du type à galette de microcanaux
FR2688343A1 (fr) * 1992-03-06 1993-09-10 Thomson Tubes Electroniques Tube intensificateur d'image notamment radiologique, du type a galette de microcanaux.
US5319189A (en) * 1992-03-06 1994-06-07 Thomson Tubes Electroniques X-ray image intensifier tube having a photocathode and a scintillator screen positioned on a microchannel array

Also Published As

Publication number Publication date
AT281142B (de) 1970-05-11
DE1764236A1 (de) 1971-07-01
NL6806736A (xx) 1968-11-18
FR1565868A (xx) 1969-05-02
SE339058B (xx) 1971-09-27
GB1154515A (en) 1969-06-11

Similar Documents

Publication Publication Date Title
US3497759A (en) Image intensifiers
US3128408A (en) Electron multiplier
US3260876A (en) Image intensifier secondary emissive matrix internally coated to form a converging lens
US3327151A (en) Light amplifier employing an electron multiplying electrode which supports a photocathode
US3660668A (en) Image intensifier employing channel multiplier plate
US3914634A (en) Channel plate acting as discrete secondary-emissive dynodes
US4041343A (en) Electron multiplier mosaic
US2403239A (en) Target electrode for electron discharge tubes
US3673457A (en) High gain storage target
US3634712A (en) Channel-type electron multiplier for use with display device
US3114044A (en) Electron multiplier isolating electrode structure
US3603832A (en) Image intensifier with channel-type secondary emission multiplier
US3400291A (en) Image intensifying tubes provided with an array of electron multiplying members
US3387137A (en) Multi-passage electron multiplier with potential differences between passageways
US2914690A (en) Electron-emitting surfaces and methods of making them
US2100259A (en) Television
US3394261A (en) Electronic intensifier device for producing a visible image from an X-ray image
US3449582A (en) Electron multiplier device having an electrically insulating secondary emission control surface
US3491233A (en) Image intensifier devices
US3461332A (en) Vacuum tubes with a curved electron image intensifying device
US2617058A (en) Television transmitting tube
US2256461A (en) Electron image tube
US3487258A (en) Image intensifier with channel secondary emission electron multiplier having tilted channels
US3688143A (en) Multi-diode camera tube with fiber-optics faceplate and channel multiplier
US3634690A (en) Tubular photocell with secondary emission from internal surface