US3829728A - Inlet screen for an electronic optical image amplifier and method of making it - Google Patents

Inlet screen for an electronic optical image amplifier and method of making it Download PDF

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Publication number
US3829728A
US3829728A US00269355A US26935572A US3829728A US 3829728 A US3829728 A US 3829728A US 00269355 A US00269355 A US 00269355A US 26935572 A US26935572 A US 26935572A US 3829728 A US3829728 A US 3829728A
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layer
screen
carrier
optical image
coating
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US00269355A
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F Gudden
W Schubert
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Siemens AG
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Siemens AG
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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
    • H01J29/38—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

  • An inlet screen for an electronic optical image amplifier has a luminous layer placed upon a carrier which is followed by a photo cathode.
  • the invention is particularly characterized in that the luminous layer is provided from the center to the edge with an absorbing substance in a manner counteracting the dropping brightness.
  • This invention relates to an inlet screen for an electronic optical image amplifier wherein a luminous layer is placed upon a carrier and is followed by the actual photo cathode layer.
  • a luminous layer is placed upon a carrier and is followed by the actual photo cathode layer.
  • Such layer arrangements are used in electronic optical image amplifiers particularly in order to change X-rays into a radiation which has a good effect upon the photo cathode layer. Otherwise X-rays would have a very little effect upon the'photo cathode layer, since they are absorbed in the thin layer only to a very small extent.
  • An object of the present invention is to improve existing devices of this type.
  • Another object is to balance the described drop in brightness so that a uniformly bright image is produced.
  • this can be accomplished when a carrier of aluminum is used by applying thereon prior to the application of the luminous layer an absorbing layer consisting of carbon and thus constituting a blackening.
  • the application can be carried out by steaming and can be so regulated by fixed or movable screens that the layer is thinner in the radial outward direction. This results in that the reflection of the carrier increases in the same direction. This also provides an increase in the density of the radiation which is transmitted from the inlet screen edgewise upon the photo cathode.
  • suitable actuation such as an optical control of the steaming at several points, the brightness can be always precisely compensated.
  • the blackening of the carrier on the side upon which lies the luminous screen layer results in a substantial improvement in the local transmission function of the screen.
  • the stronger absorbing coating which increases from the edge toward the center improves the modulation transmission function in the particularly important center of the image without making worse the'transmission function at the edge at a predetermined radiation density, as compared to a screen having no blackenmg.
  • the distribution of light can also take place by absorbing substances which are introduced into the layer or applied thereon in suitable manner.
  • a feature of the present invention is that the drop in brightness is not compensated by making the luminous the edge it would be necessary to accept a noticeable worsening of the transmission function. On the other hand a thinner coating in the middle would result in an insufficient ray absorption.
  • FIG. 1 is a diagrammatic partly sectional view through an electronic optical X-ray image amplifier.
  • FIG. 2 is a partly sectional view illustrating the making of an inlet screen.
  • FIG. 1 shows a vacuum tight piston 1 having an inlet screen 3 behind the inlet window 2.
  • the screen is followed, for example, by electrodes 4 and 5, an anode 6 and an outlet or viewing screen 7 which can be examined through the end window 8.
  • the inlet screen made in accordance with the present invention consists of a carrier calotte 9 carrying in the middle a thicker graphite layer 10 and coated inwardly with a luminous layer 1 1.
  • FIG. 2 shows a device for producing the graphite layer 10 extending toward the side.
  • the device consists essentially of a vacuum tight jar 13 mounted upon an equally tight table 14 and evacuated by a suction joint 15.
  • evaporators l6 and 17 used to coat the calotte 18.
  • the calotte is mounted as cover upon a cylinder 19 which is mounted by rollers 20 and 21 upon the table 14 and which is also rotated by the motor 22 and the frictional wheel 23, so that the calotte 18 is uniformly coated even if the centering is not precise.
  • the coating of the calotte is determined by the light source 25 and the accordingly set measuring device 26 which can be read at an indicating device 28 connected with the device 26 by a line 27.
  • the unit is operated in that carbon vapor produced in the evaporator 17 provides a strong coating in the middle of the calotte 18 while at the sides a shadowing takes place by the screen 24 which is not strongly represented upon the calotte 18, whereby a continuous coating is produced.
  • the diameter of the opening 29 of the screen is so selected that the desired balancing of dropping brightness is produced.
  • the coating with carbon is terminated when the instrument 28 shows that percent of the passing light has been reduced to about 40 percent. Then a luminous substance can be applied by the evaporator 16. However, the screen 24 must be removed to provide a uniform thickness of the luminous coating.
  • a carrier calotte 9 which consists of metal and is not transparent
  • the control of the application by transmitted rays cannot be carried out.
  • a mirror shown by broken lines
  • a bundle of rays which then passes from the mirror 30 to a source 25 directed to the receiver 26, can be collected then in the receiver 26 which corresponds to the measuring device 26 and can be further treated in the same manner as in the above-described devices 26 to 28.
  • the vapor application can be also controlled in time. However, reproduction requirements must be met.
  • the data of the vapor application means are set according to data produced by experience. The control can be also strengthened by the visual observation of the vapor application.
  • an inlet screen comprising an outer carrier, a photo cathode layer, a luminous layer extending between said carrier and said photo cathode layer and carried by said carrier, and a coating of a light absorbent substance carried by said luminous layer upon the side thereof directed toward said carrier and being the rear side relatively to said photo cathode layer, the thickness of said coating diminishing from the center toward the edges of said layer to balance the dropping brightness of the layer.

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  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)

Abstract

An inlet screen for an electronic optical image amplifier has a luminous layer placed upon a carrier which is followed by a photo cathode. The invention is particularly characterized in that the luminous layer is provided from the center to the edge with an absorbing substance in a manner counteracting the dropping brightness.

Description

United States Patent 1191 Gudden et a1.
[ Aug. 13, 1974 INLET SCREEN FOR AN ELECTRONIC OPTICAL IMAGE AMPLIFIER AND METHOD OF MAKING IT Inventors: Friedrich Gudden, Erlangen;
Wolfgang Schubert, Frauenaurach, both of Germany Assignee: Siemens Aktiengesellschaft,
Erlangen, Germany Filed: July 6, 1972 Appl. No.: 269,355
Foreign Application Priority Data July 8, 1971 Germany..' 2134110 US. Cl. ..3 13 101 Int. Cl. HOlj 31/50 Field of Search 313/65 12,65 A, 94, 101
[56] References Cited UNITED STATES PATENTS 3,617,791 11/1971 Franz 313/94 3,716,713 2/1973 Levin 313/65 R X Primary Examiner-Herman Karl Saalbach Assistant ExaminerSiegfried H. Grimm Attorney, Agent, or Firm-Richards & Geier [5 7] ABSTRACT An inlet screen for an electronic optical image amplifier has a luminous layer placed upon a carrier which is followed by a photo cathode. The invention is particularly characterized in that the luminous layer is provided from the center to the edge with an absorbing substance in a manner counteracting the dropping brightness.
3 Claims, 2 Drawing Figures INLET SCREEN FOR AN ELECTRONIC OPTICAL IMAGE AMPLIFIER AND METHOD OF MAKING IT This invention relates to an inlet screen for an electronic optical image amplifier wherein a luminous layer is placed upon a carrier and is followed by the actual photo cathode layer. Such layer arrangements are used in electronic optical image amplifiers particularly in order to change X-rays into a radiation which has a good effect upon the photo cathode layer. Otherwise X-rays would have a very little effect upon the'photo cathode layer, since they are absorbed in the thin layer only to a very small extent.
In known image amplifiers having an inlet screen of the described type the brightness drops in the outgoing image, namely, parts having the same brightness appear darker at the edge than in the middle.
An object of the present invention is to improve existing devices of this type.
Another object is to balance the described drop in brightness so that a uniformly bright image is produced.
Other objects of the present invention will become apparent in the course of the following specification.
In the accomplishment of the objectives of the present invention it was found possible to provide uniform brightness reproduction in outgoing images of image amplifiers by providing a layer upon the luminous screen which absorbs the light of radiation from the center toward the edge opposite to the drop in brightness.
In accordance with the present invention this can be accomplished when a carrier of aluminum is used by applying thereon prior to the application of the luminous layer an absorbing layer consisting of carbon and thus constituting a blackening. The application can be carried out by steaming and can be so regulated by fixed or movable screens that the layer is thinner in the radial outward direction. This results in that the reflection of the carrier increases in the same direction. This also provides an increase in the density of the radiation which is transmitted from the inlet screen edgewise upon the photo cathode. By suitable actuation, such as an optical control of the steaming at several points, the brightness can be always precisely compensated.
The central coating can be so selected that the total increase of the image amplifier (Gx) can have any desired value within certain limits (for example, Gx lcd s/m mR, wherein cd =candela, s =seconds, m square meters and mR milliroentgens.)
The blackening of the carrier on the side upon which lies the luminous screen layer results in a substantial improvement in the local transmission function of the screen. The stronger absorbing coating which increases from the edge toward the center improves the modulation transmission function in the particularly important center of the image without making worse the'transmission function at the edge at a predetermined radiation density, as compared to a screen having no blackenmg.
lnstead of using the above-described reflection diminishing layer, the distribution of light can also take place by absorbing substances which are introduced into the layer or applied thereon in suitable manner.
A feature of the present invention is that the drop in brightness is not compensated by making the luminous the edge it would be necessary to accept a noticeable worsening of the transmission function. On the other hand a thinner coating in the middle would result in an insufficient ray absorption.
The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing showing by way of example only, a preferred embodiment of the inventive idea.
In the drawing:
FIG. 1 is a diagrammatic partly sectional view through an electronic optical X-ray image amplifier.
FIG. 2 is a partly sectional view illustrating the making of an inlet screen.
FIG. 1 shows a vacuum tight piston 1 having an inlet screen 3 behind the inlet window 2. The screen is followed, for example, by electrodes 4 and 5, an anode 6 and an outlet or viewing screen 7 which can be examined through the end window 8. The inlet screen made in accordance with the present invention consists of a carrier calotte 9 carrying in the middle a thicker graphite layer 10 and coated inwardly with a luminous layer 1 1.
When X-rays pass through the window 2, the carrier 9 and the graphite layer 10 into the luminous layer 11, light is released therein which penetrates into the photo cathode layer 12, which releases these electrons; the electrodes 4, 5 and the anode 6 transmit them upon the screen 7. Due to the acceleration of the electrons and due to the diminution of the image a substantially brighter image is produced in the screen than could have been expected from the luminosity.
FIG. 2 shows a device for producing the graphite layer 10 extending toward the side. The device consists essentially of a vacuum tight jar 13 mounted upon an equally tight table 14 and evacuated by a suction joint 15. Within the cover 13 there are evaporators l6 and 17 used to coat the calotte 18. The calotte is mounted as cover upon a cylinder 19 which is mounted by rollers 20 and 21 upon the table 14 and which is also rotated by the motor 22 and the frictional wheel 23, so that the calotte 18 is uniformly coated even if the centering is not precise. Furthermore shortly before the calotte l8 and within the cylinder 19 there is a screen 24 having a free passage in the middle for the strong treatment of the calotte 18. The coating of the calotte is determined by the light source 25 and the accordingly set measuring device 26 which can be read at an indicating device 28 connected with the device 26 by a line 27.
The unit is operated in that carbon vapor produced in the evaporator 17 provides a strong coating in the middle of the calotte 18 while at the sides a shadowing takes place by the screen 24 which is not strongly represented upon the calotte 18, whereby a continuous coating is produced. The diameter of the opening 29 of the screen is so selected that the desired balancing of dropping brightness is produced.
The coating with carbon is terminated when the instrument 28 shows that percent of the passing light has been reduced to about 40 percent. Then a luminous substance can be applied by the evaporator 16. However, the screen 24 must be removed to provide a uniform thickness of the luminous coating.
When a carrier calotte 9 is used which consists of metal and is not transparent, the control of the application by transmitted rays cannot be carried out. However, a mirror (shown by broken lines) can be placed within the range of the screen 24 and a testing glass 31 is placed in the ray passage. A bundle of rays which then passes from the mirror 30 to a source 25 directed to the receiver 26, can be collected then in the receiver 26 which corresponds to the measuring device 26 and can be further treated in the same manner as in the above-described devices 26 to 28.
The vapor application can be also controlled in time. However, reproduction requirements must be met. The data of the vapor application means are set according to data produced by experience. The control can be also strengthened by the visual observation of the vapor application.
What is claimed is:
1. In an electronic optical image amplifier, an inlet screen comprising an outer carrier, a photo cathode layer, a luminous layer extending between said carrier and said photo cathode layer and carried by said carrier, and a coating of a light absorbent substance carried by said luminous layer upon the side thereof directed toward said carrier and being the rear side relatively to said photo cathode layer, the thickness of said coating diminishing from the center toward the edges of said layer to balance the dropping brightness of the layer.
2. A screen in accordance with claim 1, wherein said absorbent substance is carbon.
3. A screen in accordance with claim 1, wherein the absorbent coating sets the increase (Gx) of the amplifier according to the formula Gx l00cd s/m mR, wherein cd =candela, s =seconds, m =square meters and mR milliroentgens.

Claims (3)

1. In an electronic optical image amplifier, an inlet screen comprising an outer carrier, a photo cathode layer, a luminous layer extending between said carrier and said photo cathode layer and carried by said carrier, and a coating of a light absorbent substance carried by said luminous layer upon the side thereof directed toward said carrier and being the rear side relatively to said photo cathode layer, the thickness of said coating diminishing from the center toward the edges of said layer to balance the dropping brightness of the layer.
2. A screen in accordance with claim 1, wherein said absorbent substance is carbon.
3. A screen in accordance with claim 1, wherein the absorbent coating sets the increase (Gx) of the amplifier according to the formula Gx 100cd s/m2 mR, wherein cd candela, s seconds, m2 square meters and mR milliroentgens.
US00269355A 1971-07-08 1972-07-06 Inlet screen for an electronic optical image amplifier and method of making it Expired - Lifetime US3829728A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2134110A DE2134110B2 (en) 1971-07-08 1971-07-08 Input screen for electron optical image intensifier and method for producing a gradual layer of the input screen

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4725724A (en) * 1985-04-26 1988-02-16 U.S. Philips Corporation Radiographic image intensifier
US4880965A (en) * 1987-03-13 1989-11-14 Kabushiki Kaisha Toshiba X-ray image intensifier having variable-size fluorescent crystals
US5171996A (en) * 1991-07-31 1992-12-15 Regents Of The University Of California Particle detector spatial resolution
US20020089196A1 (en) * 1998-07-29 2002-07-11 Porter Marshall Ray Bumper beam extensions

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5773853U (en) * 1980-10-22 1982-05-07
FR2545270B1 (en) * 1983-04-29 1985-12-27 Thomson Csf RADIOLOGICAL IMAGE INTENSIFIER AND APPLICATION TO A DIGITAL RADIOLOGY SYSTEM
NL8900040A (en) * 1989-01-09 1990-08-01 Philips Nv ROENTGEN IMAGE AMPLIFIER TUBE WITH SELECTIVE FILTER.
DE102007050437A1 (en) * 2007-10-22 2009-04-23 Siemens Ag Scintillator for use in e.g. X-ray diagnostic device, has luminescent layer converting radiation into visible light, where distribution of light from luminescent layer is adapted to projection lens by anti-vignetting measures

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4725724A (en) * 1985-04-26 1988-02-16 U.S. Philips Corporation Radiographic image intensifier
US4880965A (en) * 1987-03-13 1989-11-14 Kabushiki Kaisha Toshiba X-ray image intensifier having variable-size fluorescent crystals
US5171996A (en) * 1991-07-31 1992-12-15 Regents Of The University Of California Particle detector spatial resolution
US20020089196A1 (en) * 1998-07-29 2002-07-11 Porter Marshall Ray Bumper beam extensions

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FR2144827B3 (en) 1975-08-29
DE2134110B2 (en) 1978-09-14
DE2134110A1 (en) 1973-01-18
FR2144827A1 (en) 1973-02-16

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