Multi-function day/night observation, ranging, and sighting device and method of its operation

• US 5,892,617 A
• Filed: 07/28/1997
• Issued: 04/06/1999
• Est. Priority Date: 07/28/1997
• Status: Expired due to Term

• Current Assignee: L-3 Communications Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Inventors: Wallace, Robert E.
• Primary Examiner(s): HENRY, JON W
• Application Number:
  US08/901,416
• Time in Patent Office: 617 Days
• Field of Search: 359/353, 359/356, 359/400, 359/419, 356/5.01, 356/5.04, 89/41.19
• US Class Current: 359/353
• CPC Class Codes: G02B 23/12 with means for image conversion or intensification

Abstract

A multi-function day/night observation, ranging, and sighting device includes a single first lens and a single eyepiece lens and provides an image of a scene. The single first lens leads to a visible-light first optical path and to an invisible-light second optical path. The invisible-light second optical path includes an image intensifier tube providing a visible image. The first and second optical paths converge with visible images provided by each pathway being overlaid at a reticule plane. A single light path leads from the reticule plane to the eyepiece lens. A laser provides a pulse of laser light projected into the scene via the single first lens, and the image intensifier tube is used as a detector for a portion of the laser light pulse reflected from an object in the scene in order to provide a laser range finding function. The device includes a light-emitting display visible through the eyepiece lens and providing ranging information superimposed over the image of the scene as seen by a user of the device. Methods of the device'"'"'s operation are also disclosed.

Claims

1. A day/night sight comprising:

a first lens receiving light from a distant scene, an eyepiece lens providing an image of the distant scene, an image intensifier tube receiving light via said first lens and responsively providing a visible image available at said eyepiece lens, a prism assembly passing light to both said image intensifier tube and to said eyepiece lens, and a laser light source providing a beam of laser light into said prism assembly, said prism assembly including a surface reflecting said laser light beam into said scene via said first lens.

2. A day/night sighting device comprising:

a first lens receiving light from a distant scene into an optical pathway;

a prism assembly bifurcating said optical pathway, one branch of the bifurcated optical pathway leading to an eyepiece lens, another branch of said optical pathway leading to an image intensifier tube responsively providing a visible image replicating said scene, a branch of said optical pathway extending from said image intensifier tube to said eyepiece lens;

a laser light source projecting a laser light beam having a certain wavelength into said prism assembly;

said prism assembly including a reflective surface directing said laser light beam into said scene via said first lens.

3. The day/night sighting device of claim 2 in which said prism assembly includes a first pair of prism members cooperatively defining a first reflective interface having a reflective-transmissive dichroic coating, and a second pair of prism members cooperatively defining another reflective interface having a reflective-transmissive dichroic coating.

4. The day/night sighting device of claim 3 wherein said another reflective interface provides said reflective surface.

5. The day/night sighting device of claim 4 in which said reflective-transmissive dichroic coating at said another reflective interface substantially reflects infrared light at said certain wavelength while substantially transmitting visible light.

6. The day/night sighting device of claim 4 wherein said reflective-transmissive dichroic coating at said first reflective interface includes a central coating portion which substantially reflects infrared light at said certain wavelength, and a surrounding coating portion which substantially passes infrared light at wavelengths shorter than said certain wavelength while substantially reflecting visible light.

7. The day/night sighting device of claim 2 further including means for selectively changing a divergence angle of said laser light beam.

8. The day/night sighting device of claim 7 in which said means for selectively changing a divergence angle of said laser light beam includes a lens movable relative to said prism assembly.

9. The day/night sighting device of claim 8 in which said laser light source includes a laser diode, a fixed lens associated with said laser diode to direct a beam of laser light toward said prism assembly, and said lens movable relative to said prism assembly being interposed between said fixed lens and said prism assembly.

10. A method of providing day/night viewing of a distant scene as well as illumination of the distant scene using laser light, said method comprising steps of:

providing a first lens receiving light from the distant scene;

disposing a prism assembly in association with the first lens to bifurcate an optical pathway;

leading one branch of the bifurcated optical pathway to an eyepiece lens to provide a visible image, and leading another branch of the bifurcated optical pathway to an image intensifier tube;

causing the image intensifier tube to responsively providing a visible image replicating the scene, and extending a branch of the optical pathway from the image intensifier tube to the eyepiece lens to present the replica visible image;

projecting a laser light beam having a certain wavelength into the prism assembly;

providing the prism assembly with a reflective surface; and

utilizing the reflective surface of the prism assembly to direct the laser light beam into the scene via the first lens.

11. The method of claim 10 further including the steps of:

including in said prism assembly a first pair of prism members cooperatively defining a first reflective interface having a reflective-transmissive dichroic coating; and

providing in said prism assembly a second pair of prism members cooperatively defining another reflective interface having a reflective-transmissive dichroic coating.

12. The method of claim 11 further including the step of using said another reflective interface to define said reflective surface.

13. The method of claim 12 including the step of using said reflective-transmissive dichroic coating at said another reflective interface to substantially reflect infrared light while substantially transmitting visible light.

14. The method of claim 13 further including steps of providing said reflective-transmissive dichroic coating at said first reflective interface with a central coating portion;

utilizing said central coating portion to substantially reflect infrared light at said certain wavelength; and

providing a surrounding coating portion at said first reflective-transmissive interface which substantially passes infrared light at wavelengths shorter than said certain wavelength while substantially reflecting visible light.

15. A day/night sight with laser illumination comprising:

a first lens receiving light from a distant scene and projecting laser light into the distant scene, an eyepiece lens providing an image of the distant scene, an image intensifier tube receiving light via said first lens and responsively providing a visible image available at said eyepiece lens, a prism assembly passing light to both said image intensifier tube and to said eyepiece lens, and a laser light source providing a beam of infrared laser light into said prism assembly, said prism assembly including a first pair of prism members defining a first reflective-transmissive interface, and a second pair of plate-like prism members disposed adjacent to a surface of one of said first pair of prism members and defining a second reflective transmissive interface, a dichroic coating provided on said second reflective-transmissive interface which substantially passes visible light while substantially reflecting infrared laser light from said laser light source at said certain wavelength into said first pair of prism members, a two-part dichroic coating on said first reflective-transmissive interface which includes a central portion substantially reflecting infrared laser light at said certain wavelength from said first pair of prism members into said distant scene via said first lens, and a surrounding coating portion which substantially reflects visible light into said second pair of prism members while substantially passing infrared light at wavelengths shorter than said certain wavelength through said first pair of prism members and to said image intensifier tube.

16. A day/night sighting and laser illumination device comprising:

a single first lens receiving light from a distant scene into an optical pathway and projecting laser light into said scene;

a dichroic prism assembly bifurcating said optical pathway, one branch of the bifurcated optical pathway leading visible light to an eyepiece lens, another branch of said optical pathway leading infrared light to an image intensifier tube responsively providing a visible image replicating said scene, a branch of said optical pathway leading said replicating visible image to said eyepiece lens;

a laser light source projecting a laser light beam having a certain wavelength into said dichroic prism assembly;

said prism assembly including a dichroic reflective surface directing said laser light beam into said scene via said first lens while substantially passing visible light to said eyepiece lens.

17. The day/night sighting device of claim 16 in which said dichroic prism assembly includes a first pair of prism members cooperatively defining a first reflective interface having a reflective-transmissive dichroic coating, and a second pair of plate-like prism members disposed adjacent to a surface of one of said first pair of prism members and cooperatively defining another reflective interface having a reflective-transmissive dichroic coating.

18. The day/night sighting device of claim 17 in which said reflective-transmissive dichroic coating at said another reflective interface substantially reflects infrared light at said certain wavelength while substantially transmitting visible light.

19. The day/night sighting device of claim 17 in which said reflective-transmissive dichroic coating at said first reflective interface substantially reflects visible light to said eyepiece lens while substantially transmitting infrared light to said image intensifier tube.

20. The day/night sighting device of claim 19 wherein said reflective-transmissive dichroic coating at said first reflective interface includes a central coating portion which substantially reflects infrared light at said certain wavelength, and a surrounding coating portion which substantially passes infrared light at wavelengths shorter than said certain wavelength while substantially reflecting visible light.