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US3617801A Expired / Lapsed US ⏱️ 0.0 years remaining

Intensity control and signal enhancement correlation tube

Assignee: Lockheed Martin Tactical Systems Inc
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Filing: 1968-05-23
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Granted: 1971-11-02
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Expires: 1988-05-23
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Abstract

Abstract The invention consists of a variable transmission field mesh which has the unique capability of isolating the uniform, accelerating electrostatic field in the photocathode region from the focus field in the drift tube while both regions are effectively isolated from the control signal. This isolation controls the electronic image intensity after the image has been generated by the photocathode, but before the image enters appreciably in the drift-tube region, without seriously degrading characteristics of the image tube such as sensitivity, resolution, and image distortion. The invention also contemplates intensity control of the output signal from the tube by actually sensing the intensity of the electron image as well as the transmisivity of the storage grid and feeding the resulting signal back to the variable transmission field mesh. A preferable construction is with a double-decked sandwich field mesh consisting of three conducting, aligned meshes separated by two insulating or vacuum layers. The middle mesh is the control mesh while the one facing the photocathode controls the field at the photocathode and the mesh facing the drift-tube maintains the drift-tube electrostatic field at essentially zero. The potential on the control mesh may vary from a value considerably below the potentials of the other two meshes for low transmission to considerably above for high transmission. Essentially, the invention relates to an electronic iris for controlling intensity of the signal in an electronic correlation tube through signal enhancement or intensity control utilizing a control mesh in association with the storage grid. Essentially, the invention relates to an electronic iris for controlling intensity of the signal in an electronic correlation tube through signal enhancement or intensity control utilizing a control mesh in association with the storage grid. Heretofore, it has been well known to utilize electronic image storage tubes for the purpose of correlation of similar optical images, such as shown in prior art U.S. Pat. Nos. 3,290,546 and 3,239,766. However, in these prior art systems there is no control for the particular intensity or light conditions of the optical input images. Therefore, for example, when the optical input image is an actual present image, the light intensity can vary considerably depending upon the atmospheric conditions and the actual location of the detector. Some type of iris control or shutter control is necessary, be it mechanical or electrical, to appropriately control the light intensity so that an image of constant average intensity is achieved. The general object of the invention is to meet the needs of the art by providing an electronic iris and intensity enhancement or reduction control in a correlation tube by controlling the signal in proportion to the intensity of the optical input signal, either before storage on the storage mesh, or after the storage mesh has performed its storage function, so as to provide an image of average intensity in both the write and read modes of operation. The aforesaid object of the invention and other objects which will become apparent as the description proceeds are achieved by providing in a correlation tube the combination of a closed tube drawn to a vacuum, a photocathode at one end of the tube, and an electrical anode at the other end thereof, means to direct and focus electrons emitted from the cathOde down the tube towards the anode, a storage mesh mounted in the tube between the cathode and anode adapted to collect electrons and represent an optical image depicted by the electrons as an electrical image, and means to control the storage capability of the storage mesh in proportion to the intensity of the light impinging on the photocathode.

Inventors

  • 👤 James J Hogan

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-06 00:28
CPC Classifications
H; H01; H01J; H01J31/00; H01J31/08; H01J31/26; H01J31/28; H01J31/286

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 171 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by the emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, mesh means positioned between the cathode and the storage grid to control the number of electrons passing to the chargeable surface in proportion to the number of secondary emission electrons from the electron chargeable surface, and a collector mesh positioned closely adjacent the chargeable surface towards the cathode, the potential on the field mesh varying in direct proportion to the potential on the collector mesh.
Claim 2
Dependent Claim 171 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by the emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, mesh means positioned between the cathode and the storage grid to control the number of electrons passing to the chargeable surface in proportion to the number of secondary emission electrons from the electron chargeable surface, and a collector mesh positioned closely adjacent the chargeable surface towards the cathode, the potential on the field mesh varying in direct proportion to the potential on the collector mesh.
Claim 3
Dependent Claim 175 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, a transmission field mesh positioned in spaced-parallel relation between the cathode and the electrOn chargeable surface to control the number of electrons passing through the chargeable surface, means to provide the field mesh with variable current control, and a collector mesh positioned closely adjacent the electron chargeable surface and toward the cathode, the current on the collector mesh controlling the means to provide variable current control to the field mesh.
Claim 4
Dependent Claim 175 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, a transmission field mesh positioned in spaced-parallel relation between the cathode and the electrOn chargeable surface to control the number of electrons passing through the chargeable surface, means to provide the field mesh with variable current control, and a collector mesh positioned closely adjacent the electron chargeable surface and toward the cathode, the current on the collector mesh controlling the means to provide variable current control to the field mesh.
Claim 5
Dependent Claim 64 words
A tube according to claim 2 where the field mesh comprises three separate meshes in closely spaced, aligned insulated relationship with the potential on each outside mesh remaining constant to maintain electronic transmission from the photocathode to the chargeable surface uniform, and with the current from the collector mesh fed back to control the means to provide variable current control to the field mesh.
Claim 6
Dependent Claim 151 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, a collector mesh in closely space, adjacent relation to the chargeable surface between the chargeable surface and the cathode, and means to pick the current off the collector mesh and feed forward to the anode to control the amplification of the voltage potential from the anode.
Claim 7
Dependent Claim 151 words
A correlation tube having intensity control which comprises an enclosed housing drawn to a vacuum, a cathode at one end of the housing to convert light images into electronic images by emission of electrons therefrom down the tube, an electron chargeable surface positioned in spaced-parallel relation to the cathode inside the housing adapted when under no charge to receive the impingement of electrons to thereby effect an electrical charge thereon to represent the light images electronically, an anode at the other end of the tube to receive any electrons passing through the electron chargeable surface and represent the number thereof as a variable voltage potential, a collector mesh in closely space, adjacent relation to the chargeable surface between the chargeable surface and the cathode, and means to pick the current off the collector mesh and feed forward to the anode to control the amplification of the voltage potential from the anode.
Claim 8
Dependent Claim 155 words
A correlation tube comprising a closed tube drawn to a vacuum, a photocathode at one end of the tube, and an electrical anode at the other end thereof, means to direct and focus electrons emitted from the cathode down the tube toward the anode, a storage mesh mounted in the tube between the cathode and anode adapted to collect electrons and represent an optical image deposited by the electrons as an electrical image, a collector mesh positioned closely adjacent the storage mesh to detect secondary emission electrons, and means to control the number of electrons impinging on the storage mesh in proportion to the intensity of the light impinging on the photocathode, the means comprising a transmission mesh which includes three separate meshes in closely spaced, aligned and insulated relationship and means to maintain an essentially constant voltage potential on the two outer meshes with the central mesh voltage proportional to the collector mesh potential.
Claim 9
Dependent Claim 155 words
A correlation tube comprising a closed tube drawn to a vacuum, a photocathode at one end of the tube, and an electrical anode at the other end thereof, means to direct and focus electrons emitted from the cathode down the tube toward the anode, a storage mesh mounted in the tube between the cathode and anode adapted to collect electrons and represent an optical image deposited by the electrons as an electrical image, a collector mesh positioned closely adjacent the storage mesh to detect secondary emission electrons, and means to control the number of electrons impinging on the storage mesh in proportion to the intensity of the light impinging on the photocathode, the means comprising a transmission mesh which includes three separate meshes in closely spaced, aligned and insulated relationship and means to maintain an essentially constant voltage potential on the two outer meshes with the central mesh voltage proportional to the collector mesh potential.

References Cited (Backward Citations)

US3349231A Cited
US3424937A Cited
US3435275A Cited
US3476197A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1974-11-01 1975-05-03 1975-11-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1978-11-01 1979-05-03 1979-11-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1982-11-01 1983-05-03 1983-11-02 $7700.00 Window Closed / Lapsed

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