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Publication numberUS2198479 A
Publication typeGrant
Publication dateApr 23, 1940
Filing dateNov 3, 1937
Priority dateNov 3, 1937
Publication numberUS 2198479 A, US 2198479A, US-A-2198479, US2198479 A, US2198479A
InventorsIrving Langmuir
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Image reproduction
US 2198479 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

pril 23, 1940. 1 LANGMUlR 2,198,479

IMAGE REPRODUCTION Filed Nov. 3, 1937 FLUORESCENT Inventor Irving) Lam muir,

Hiq Attorney.

Patented Apr. 23, 1940 UNITED STATES PATENT OFFICE to General Electric of New York Company, a corporation Application November s, 1937, serial No. 172,509

3 Claims.

The present invention relates to image reproduction, and more particularly to improvements in image reproduction systems of the type described and claimed in Patent No. 2,158,853 of4 5 W. D. Coolidge, granted May 16, 1939, and assigned to the General Electric Company.

The aforementioned Coolidge patent discloses apparatus by means of which a relatively Weak or transitory primary visible image produced by a source of radiation, for example X-rays (including gamma-rays) or other ultra-visible radiations may be converted into a secondary visible image of substantially greater intensity or greater This is ac.

face which comprises fluorescent and photoelectric materials in close mechanical association.

The features of novelty which I desire to protect herein will be pointed out with particularity in the appended claims. The-invention itself, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the drawing, in which Fig.A 1 shows in partial section an image reproduction system suitably embodying the invention and Figs. 2 and 3 show fragmentary details of various parts of the construction of Fig. 1.

Referring particularly to Fig. 1 there is shown at the extreme left of the figure an X-ray tube comprising a cathode I0 and a target or anode II. poses radiations originating at the target II impinge upon an object to be examined, such an object being represented in the present case as a human hand I3; Radiations transmitted .through the object are caused to fall upon the end wall I5 of an evacuated transparent or translucent envelope I6, suitably of glass which constitutes the enclosure for an image reproduction device. In accordance with the invention the wall I5 is provided with common means whereby the transmitted X-radiations may be successively converted into a visible image and then into a beam of photoelectrons having a section pattern cor- In the use of this device for diagnostic pur- (Cl. Z-153) responding to that of the visible image. Such a means may include, for example, a combination of fluorescent and photoelectrlc materials applied to the inside of the wall I5. One particular combination which I consider suitable for this purpose comprises a layer of calcium tungstate supercially coated with a film of photoelectrically active material. The photoelectrlc lm is preferably at least slightly conductive in character and should be so thin as to `be substantially transparent. It may be composed, for example, of a deposit of slightly oxidized silver which has been activated with an alkali metal, preferably caesium. The physical structure of the composite surface is indicated in Fig. 2 in which I1 is a layer of a material which is adapted to iiuoresce under the influence of X-rays and I8 is a conducting transparent film comprising a photoelectric substance. In an alternative arrangement the uorescent and photoelectrlc materials may be admixed to form a single layer. Under the action of impinging X-radiations /the fluorescent material will form a visible image whose nature will be determined by that ofthe interposed object I3. The light thereby devel.- oped will in turn be effective to release electrons from vthe associated photoactive material in a pattern which corresponds closely to that of the image itself. As explained in the Coolidge application above referredto, the electrons so developed may be focused electron-optically to impinge on another fluorescent screen 20 where they will produce a secondary visible image corresponding in outline to the section pattern of the electron beam. If, during the transition'period the electrons are accelerated to a sufficiently high velocity, this secondary image may be of substantially greater intensity than the primary image. Consequently, a camera positioned as indicated at 30 may obtain a good photographic record of the image even though a relatively weak source of X-rays is employed.

In the present instance a suitable accelerating and focusing system is shown as comprising an accelerating electrode 2I adapted to be charged to a high potential with respect to the emissive lsurface I8 and an associated focusing electrode mating at the cathode surface I8 may be caused to form on the fluorescent screen 20 a clear and intensified secondary image corresponding to the primary image which appears on the surface I1. In some cases it may be desirable to augment the electron-optical lens formed by the electrodes 2| and 23 by means of additional magnetic or electrostatic focusing means.

While I have shown particular embodiments of my invention, it will be understood by those skilled in the art that many modifications may be made without departing from the invention, and I aim by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to obtain by Letters Patent of the United States is:

1. A composite electrode comprising a layer of calcium tungstate adapted to be excited to iiuorescence by the action of impinging radiations and a transparent film of oxidized silver thereon, said lm being photoelectrically activated with caesium, whereby fluorescence of the calcium tungstate layer results in electron emission from the electrode.

2. In an image-reproducing system, a source of primary radiations, an electrode exposed to the said primary radiations and having contiguously arranged uorescent and photoelectric components, the iiuorescent component being adapted to luminesce in response to impingement of the said primary radiations thereon, and the photoelectric coinponent being substantially non-emissive when excited solely by said primary radiations but being capable of effective electron emission when excited by light from the iiuorescent component, and image-reproducing means for receiving electrons emitted by the photoelectric component in response to excitation of the flucrescent component by the said primary radiations.

3. In an image-reproducing system, a source of X-rays deiining a primary image, an electrode exposed to the saidsource and having a photovelectric component arranged in direct contact with a fluorescent component which is adapted to luminesce when excited by X-rays, the said photoelectric component being substantially nonemissive when excited solely by X-rays but being

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2523132 *Aug 10, 1949Sep 19, 1950Westinghouse Electric CorpPhotosensitive apparatus
US2527913 *Aug 4, 1948Oct 31, 1950Radio Industrie SaPhotoelectric device
US2530517 *Nov 1, 1944Nov 21, 1950X Ray Electronic CorpX-ray testing and measuring method and apparatus
US2555423 *Apr 16, 1947Jun 5, 1951Emanuel Sheldon EdwardImage intensifying tube
US2555424 *Mar 9, 1948Jun 5, 1951Emanuel Sheldon EdwardApparatus for fluoroscopy and radiography
US2586391 *Jul 8, 1947Feb 19, 1952Emanuel Sheldon EdwardDevice for projection of microwave images
US2586392 *Dec 9, 1948Feb 19, 1952Emanuel Sheldon EdwardMotion-picture camera for chi-ray images
US2593925 *Oct 5, 1948Apr 22, 1952Emanuel Sheldon EdwardDevice for color projection of invisible rays
US2603757 *Nov 5, 1948Jul 15, 1952Emanuel Sheldon EdwardPhotocathode
US2612610 *Nov 6, 1948Sep 30, 1952Westinghouse Electric CorpRadiation detector
US2660539 *Feb 25, 1950Nov 24, 1953Westinghouse Electric CorpMethod for producing a fluorescent screen
US2660686 *Jun 19, 1948Nov 24, 1953Westinghouse Electric CorpFluorescent screen
US2666864 *Jan 20, 1950Jan 19, 1954Westinghouse Electric CorpImage intensifier tube
US2681868 *Aug 10, 1949Jun 22, 1954Westinghouse Electric CorpImage amplifier
US2690516 *Apr 21, 1948Sep 28, 1954Emanuel Shcldon EdwardMethod and device for producing neutron images
US2692299 *Dec 11, 1948Oct 19, 1954Westinghouse Electric CorpImage contrast intensifier
US2692300 *Jul 6, 1950Oct 19, 1954Hogan Alsede WElectric image formation and control apparatus
US2727183 *Dec 22, 1948Dec 13, 1955Westinghouse Electric CorpRadiation detector of the scanning type
US2739257 *Oct 15, 1948Mar 20, 1956Emanuel Sheldon EdwardDevice for x-ray motion pictures
US2739258 *May 19, 1950Mar 20, 1956Sheldon Edward ESystem of intensification of x-ray images
US2782332 *Apr 6, 1949Feb 19, 1957Emanuel Sheldon EdwardMethod and device for reading images of invisible radiation
US2804561 *Jun 1, 1951Aug 27, 1957Emanuel Sheldon EdwardChi-ray camera
US2864031 *Dec 30, 1950Dec 9, 1958Rca CorpElectrical storage tube
US2955219 *Feb 16, 1959Oct 4, 1960Rauland CorpElectron discharge device
US3014147 *Apr 9, 1947Dec 19, 1961Rca CorpInfra red image tube
US3400291 *Aug 28, 1964Sep 3, 1968Emanuel Sheldon EdwardImage intensifying tubes provided with an array of electron multiplying members
US3443104 *Feb 17, 1966May 6, 1969Rauland CorpImage intensifier tube with shading compensation
US3461332 *Nov 26, 1965Aug 12, 1969Edward E SheldonVacuum tubes with a curved electron image intensifying device
US3922523 *May 16, 1973Nov 25, 1975Sheldon Edward EApparatus for producing x-ray images as radiographs
US4186302 *Jul 12, 1978Jan 29, 1980Diagnostic Information, Inc.Panel type X-ray image intensifier tube and radiographic camera system
US4300046 *Aug 31, 1979Nov 10, 1981Diagnostic Information, Inc.Panel type X-ray image intensifier tube and radiographic camera system
US6895077Nov 21, 2001May 17, 2005University Of Massachusetts Medical CenterSystem and method for x-ray fluoroscopic imaging
US20030169847 *Nov 21, 2001Sep 11, 2003University Of Massachusetts Medical CenterSystem and method for x-ray fluoroscopic imaging
DE968667C *Apr 4, 1952Apr 17, 1958Philips NvBildwandler
Classifications
U.S. Classification250/214.0VT, 430/139, 313/251, 313/527
International ClassificationH01J29/10, H01J29/38
Cooperative ClassificationH01J29/385
European ClassificationH01J29/38B