Light projection system

• US 4,295,159 A
• Filed: 06/05/1980
• Issued: 10/13/1981
• Est. Priority Date: 06/05/1980
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Electric Company
• Inventors: Carollo, Jerome T., Barbarasch, Joseph
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Masinick, Michael A.
• Application Number:
  US06/156,685
• Time in Patent Office: 495 Days
• Field of Search: 358/22, 358/21 R, 358/56, 358/59, 358/60, 358/61, 358/64, 358/230, 358/231, 358/232, 358/236, 358/183, 353/30, 353/31, 353/34, 353/37, 350/359, 350/361, 350/330, 350/266
• US Class Current: 348/761
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10

Abstract

Apparatus and method are disclosed directed to a real time, electro-optical light projection system, wherein at least one selected target is displayed on a high resolution mini-raster, differentiated from a coarse resolution base raster background. A full color display of the target on a full color background is provided with three cathode ray tubes in association with corresponding liquid crystal light valves. Alternatively, a single cathode ray tube and an associated liquid crystal light valve are used to display the target monochromatically against a monochromatic background.

Claims

1. In an electro-optical light projection system for displaying an image in which at least one selected target is portrayed in a manner differentiated from its background;

said system comprising;

at least one high resolution cathode ray tube including means for generating an electron beam, a tube face responsive to said electron beam to provide a visible light image thereon, beam deflection means and beam intensity control means;

means for periodically applying base raster signals to said beam deflection means, said base raster signals being effective to cause said electron beam to scan through a base raster having a predetermined coarse spacing between successive base raster lines, said base raster covering at least the major portion of said tube face;

means concurrently operative with the application of said base raster signals for applying first control signals to said beam intensity control means representative of background information;

means for periodically applying mini-raster signals to said beam deflection means in alternation with said base raster signals, said mini-raster signals being effective to cause said electron beam to scan through a mini-raster having a predetermined close spacing between successive mini-raster lines, said mini-raster covering a restricted area within said base raster;

means concurrently operative with the application of said mini-raster signals for applying second control signals to said beam intensity control means representative of target information;

a source of collimated white light;

means for deriving polarized light from said collimated white light;

3. Apparatus in accordance with claim 1 wherein said liquid crystal light valve is fiber-optically couped to said tube face.

5. Apparatus in accordance with claim 3 wherein said target and said mini-raster are displayed monochromatically against a monochromatic background in said projected image.

6. Apparatus in accordance with claim 3 wherein said system comprises three substantially identical cathode ray tubes each having a separate liquid crystal light valve fiber-optically coupled to the tube face thereof;

means for splitting said polarized light into three different primary color light beams each directed to a different one of said light valves;

means for synchronously applying said base raster signals to the beam deflection means of each of said three cathode ray tubes alternately with said mini-raster signals;

means for alternately applying a separate one of said first control signals and of said second control signals respectively in synchronism to the beam intensity control means of each of said three cathode ray tubes, said first and second control signals being applied to said three cathode ray tubes concurrently with the application of said base raster signals and said mini-raster signals respectively;

each of said first control signals being representative of background information limited to a different primary color; and

each of said second control signals being representative of target information limited to the same primary color as the corresponding first control signals applied to the same cathode ray tube;

whereby said target and said mini-raster are portrayed in full color against a full color background.

8. Apparatus in accordance with claim 6 wherein said means for deriving three polarized primary color light beams comprises:

a prism adapted to provide a pair of light beam components having different states of light polarization;

and

a combination of color-specific dichroic mirror means and color-specific trim filter means jointly adapted to split at least one of said polarized light beam components to derive said three beams having different primary colors.

10. Apparatus in accordance with claim 6 wherein said means for deriving three polarized light beams having different primary colors and said beam combining means comprise:

a prism positioned in the light path of said source, said prism being adapted to split said collimated white light into a pair of orthogonally complementary, linearly polarized beam components;

blue dichroic mirror means positioned in the path of a first one of said polarized beam components for separating a polarized blue beam therefrom;

a first one of said light valves being positioned coaxial with the path of said polarized blue beam to receive the latter;

a blue trim filter positioned between said blue dichroic mirror and said first light valve adapted to admit only substantially pure primary blue light to the latter valve;

a first red dichroic mirror positioned in the path of the other one of said polarized beam components for separating a pair of mutually orthogonal beams therefrom consisting substantially of polarized blue and green light and of polarized red light respectively;

a second one of said light valves being positioned coaxial with the path of said polarized blue and green beam to receive the latter;

a green trim filter positioned between said first red dichroic mirror and said second light valve adapted to admit only substantially pure primary green light to the latter valve;

a second red dichroic mirror positioned in the path of said red beam and adapted to re-direct the latter, said second red mirror being adapted to reflect only substantially pure primary red light;

a third light valve positioned coaxial with the path of said re-directed red beam to receive the latter; and

said prism being further adapted to combine said reflected primary color light beams to provide said single full color light beam.

12. The method in accordance with claim 10 wherein said target and said mini-raster are displayed monochromatically on said screen against a monochromatic background.

13. The method in accordance with claim 10 wherein at least three substantially identical cathode ray tubes are used each having a separate liquid crystal light valve fiber-optically coupled to the tube face thereof;

said base raster signals being applied in synchronism to said three cathode ray tubes alternately with the synchonous application of said mini-raster signals;

said first control signals being applied in synchronism to said three cathode ray tubes, each of said first control signals being representative of background information limited to a different primary color;

said second control signals being applied in synchronism to said three cathode ray tubes, each of said second control signals being representative of target information limited to the same primary color as the corresponding first control signals applied to the same cathode ray tube;

deriving three polarized light beams having different primary colors from said polarized light, each of said last-recited light beams being directed to a different one of said light valves for reflection therefrom as a polarization-modulated primary color light beam; and

combining said polarization-modulated primary color light beams into a single, full color light beam for projection onto said screen;

whereby said target and said mini-raster are displayed in full color on said screen against a full color background.

2. a liquid crystal light valve associated with said cathode ray tube and positioned to receive and reflect said polarized light, said light valve being responsive to the variable light image on said tube face modulate the polarization of the light beam reflected by said light valve;

a display screen; and

means for projecting said polarization-modulated light beam onto said display screen;

whereby a magnified, real time image is provided on said screen adapted to display said target on said mini-raster in high resolution detail, differentiated from the low resolution background displayed by said base raster.

4. Apparatus in accordance with claim 2 wherein said means for deriving polarized light includes a prism adapted to split said collimated white light into a pair of orthogonally complementary linearly polarized beam components.

7. In an electro-optical light projection system for displaying an image in which at least one selected target is portrayed in a manner differentiated from its background;

said system comprising;

a source of collimated white light;

means for deriving three polarized light beams from said collimated white light each having a different primary color;

first, second and third high resolution cathode ray tubes;

each of said cathode ray tubes including means for generating an electron beam, a tube face responsive to said electron beam for producing a visible light image thereon, beam deflection means and beam intensity control means;

means for periodically applying base raster signals in synchronism to respective ones of said beam deflection means, each of said base raster signals being effective to cause the corresponding electron beam to scan through a base raster having a predetermined coarse spacing between successive base raster lines, said base raster covering at least the major portion of said tube face;

means concurrently operative with the application of said base raster signals for applying first control signals in synchronism to respective ones of said beam intensity control means, each of said first control signals being representative of background information limited to a different primary color;

means for periodically applying mini-raster signals in synchronism to respective ones of said beam deflection means in alternation with said base raster signals, each of said mini-raster signals being effective to cause the corresponding electron beam to scan through a mini-raster having a predetermined close spacing between successive mini-raster lines, said mini-raster covering a restricted area within said base raster;

means concurrently operative with the application of said mini-raster signals for applying second control signals in synchronism to respective ones of said beam intensity control means, each of said second control signals being representative of target information limited to the same primary color as the corresponding first control signals applied to the same cathode ray tube;

a separate liquid crystal light valve fiber-optically coupled to each of said tube faces, each of said light valves being positioned to receive and reflect a separate one of said primary color polarized light beams, each of said light valves being responsive to the variable light image on the tube face coupled thereto to modulate the polarization of the primary color light beam reflected by said light valve;

means for combining said reflected, primary color light beams into a single, full color light beam;

a display screen; and

means for projecting said full color light beam onto said display screen;

whereby a magnified, real time image is provided on said screen adapted to display said target on said mini-raster in full color, high resolution detail, differentiated from the full color, low resolution background displayed by said base raster.

9. Apparatus in accordance with claim 7 wherein said prism further comprises said beam combining means.

11. A method for using a high-intensity source of collimated white light in association with at least one high resolution cathode ray tube and a liquid crystal light valve fiber-optically coupled to the face of said tube to display an image on a display screen wherein at least one selected target is portrayed in a manner differentiated from its background;

said method comprising the steps of;

periodically applying base raster signals to said cathode ray tube effective to cause the electron beam thereof to scan through a base raster on the face of said tube, said base raster having a predetermined coarse spacing between successive base raster lines and covering at least the major portion of said tube face;

applying first control signals to said cathode ray tube concurrently with the application of said base raster signals, said first control signals being adapted to control the intensity of said electron beam in accordance with information representative of said background;

periodically applying mini-raster signals to said cathode ray tube in alternation with said base raster signals, said mini-raster signals being effective to cause said electron beam to scan through a mini-raster on said tube face having a predetermined close spacing between successive mini-raster lines and covering a restricted area within said base raster;

applying second control signals to said cathode ray tube concurrently with the application of said mini-raster signals, said second control signals being adapted to control the intensity of said electron beam in accordance with information representative of said target;

deriving polarized light from said collimated white light;

directing said polarized light to said light valve for reflection therefrom;

modulating the polarization of the light beam reflected from said light valve in accordance with the variable light image provided on said tube face; and

projecting said polarization-modulated light beam onto said display screen;

whereby a magnified, real time image is provided on said screen to display said target on said mini-raster in high resolution detail, differentiated from the low resolution background displayed by said base raster.