Direct view zoom scope with single focal plane and adaptable reticle

• US 9,494,787 B1
• Filed: 03/12/2013
• Issued: 11/15/2016
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Bagwell, Brett
• Primary Examiner(s): Won, Bumsuk
• Assistant Examiner(s): Duong, Henry
• Application Number:
  US13/797,607
• Time in Patent Office: 1,344 Days
• Field of Search: 359421-729
• US Class Current: 1/1
• CPC Class Codes: F41G 1/17 Convertible sights, i.e. sets of two or more sights brought into the sight line optionally
• CPC Class Codes: F41G 1/38 Telescopic sights specially adapted for smallarms or ordnance telescopic sights in general G02B; Supports or mountings therefor
• CPC Class Codes: G02B 17/045 having static image erecting or reversing properties only optical derotators G02B27/642; optical devices for controlling the direction of light using movable or deformable optical elements G02B26/08
• CPC Class Codes: G02B 23/145 Zoom viewfinders
• CPC Class Codes: G02B 27/32 Fiducial marks and measuring scales within the optical system
• CPC Class Codes: G02B 3/14 of variable focal length

Abstract

A direct view telescopic sight includes objective lens, eyepiece, and prism erector assemblies. The objective lens assembly is mounted to receive light of an image from an object direction and direct the light along an optical path. The eyepiece assembly is mounted to receive the light along the optical path and to emit the light of the image along an eye-ward direction. The prism erector assembly is positioned between the objective lens and eyepiece assemblies and includes first and second prism elements through which the optical path passes. The first and second prism elements invert the image. A reticle element is disposed on or adjacent to a surface of one of the first or second prism elements to combine a reticle on the image. The image is brought into focus at only a single focal plane between the objective lens and eyepiece assemblies at a given time.

Claims

1. A direct view telescopic sight, comprising:

an objective lens assembly mounted to receive collimated light of an image from an object direction and direct the light along an optical path;

an eyepiece assembly mounted to receive the light along the optical path and to emit collimated and magnified light of the image along an eye-ward direction; and

a prism erector assembly positioned within the optical path between the objective lens assembly and the eyepiece assembly, the prism erector assembly including;

first and second prism elements through which the optical path passes, wherein the first and second prism elements are oriented to redirect the optical path within the first and second prism elements to invert the image propagating along the optical path between the objective lens assembly and the eyepiece assembly, and wherein surfaces of both the first and second prism elements are each coincident with a different focal plane of a plurality of focal planes; and

a first reticle element disposed on, or immediately adjacent to without an intervening element having optical power, a first surface of one of the first or second prism elements to impose a first reticle on the image, wherein the first reticle element is associated with a first focal plane of the plurality of focal planes, and

wherein the objective lens, eyepiece, and prism erector assemblies are coupled to bring the image into focus at only one focal plane at a given time along the optical path between the objective lens and eyepiece assemblies, and wherein the only one focal plane is positioned to be coincident with one focal plane of the plurality of focal planes at the given time.

2. The direct view telescope sight of claim 1, wherein the objective lens assembly comprises:

a first adjustable lens having a first adjustable focal length; and

a second adjustable lens having a second adjustable focal length.

3. The direct view telescope sight of claim 2, wherein the objective lens assembly further comprises:

a first iris disposed adjacent to the first adjustable lens; and

a second iris disposed between the first and second adjustable lens,

wherein the first iris operates as a limiting aperture when the objective lens assembly is operating in a first zoom setting and the second iris operates as the limiting aperture when the object lens assembly is operation in a second zoom setting.

4. The direct view telescope sight of claim 2, wherein the first reticle element comprises a reflective electronic display, the direct view telescope sight further comprising:

a controller coupled to control the first reticle displayed by the first reticle element and coupled to the first and second adjustable lenses to control the first and second adjustable focal lengths.

5. The direct view telescope sight of claim 1, wherein the objective lens assembly comprises a first adjustable lens having a first adjustable focal length and the eyepiece assembly comprises a second adjustable lens having a second adjustable focal length, the direct view telescope sight of claim 1, further comprising:

a controller coupled to the first and second adjustable lenses to control the first and second adjustable focal lengths.

6. The direct view telescope sight of claim 5, wherein the prism erector assembly further comprises:

a second reticle element, different from the first reticle element, disposed on or adjacent to a second surface of one of the first or second prism elements to impose a second reticle on the image.

7. The direct view telescope sight of claim 4, wherein the controller includes logic which when executed by the controller causes the controller to output control signals to the first reticle element and the objective lens assembly that zoom the direct view telescope sight by:

adjusting focal lengths of the first and second adjustable lenses to change the field of view (“

FOV”

) of the objective lens assembly in the object direction while holding the only one focal plane at the first surface of the prism erector assembly coincident with the first focal plane of the plurality of focal planes and maintaining a size of the image focused onto the only one focal plane constant; and

adjusting a size of the first reticle displayed by the reflective electronic display while changing the FOV to maintain a constant angular meaning of marks within the first reticle relative to the image from one zoom setting to a next zoom setting.

8. The direct view telescope sight of claim 4, wherein the first and second adjustable lenses each comprise a liquid lens that adjusts shape in response to an actuator coupled to the controller.

9. The direct view telescope sight of claim 4, wherein the reflective electronic display comprises a liquid crystal on silicon (“

LCOS”

) display.

10. The direct view telescope sight of claim 4, wherein the controller includes logic which when executed by the controller causes the controller to change a type of the first reticle displayed by the first reticle element based upon a zoom setting of the objective lens assembly.

11. The direct view telescopic sight of claim 1, wherein the only one focal plane is coincident with a given surface of the first or second prism elements.

12. The direct view telescope sight of claim 6, wherein the controller includes logic which when executed by the controller causes the controller to output control signals to the first and second adjustable lens that change a zoom factor of the direct view telescope sight by:

adjusting the first and second adjustable focal lengths to reposition the only one focal plane from being coincident with the first focal plane associated with the first reticle element to being coincident with a second focal plane of the plurality of focal planes, wherein the second reticle element is associated with the second focal plane of the plurality of focal planes,

wherein only a selected one of the first or second reticle elements is in-focus and viewable through the eyepiece assembly at a given time.

13. The direct view telescope sight of claim 12, wherein the prism erector assembly further comprises a third reticle element, different from the first and second reticle elements, disposed on or adjacent to a third surface of one of the first or second prism elements to impose a third reticle on the image, and wherein the controller includes further logic which when executed by the controller causes the controller to output control signals to the first and second adjustable lens that change the zoom factor of the direct view telescope sight by:

adjusting the first and second adjustable focal lengths to reposition the one focal plane from being coincident with the second focal plane associated with the second reticle element to being coincident with a third focal plane of the plurality of focal planes, wherein the third reticle element is associated with the third focal plane.

14. The direct view telescope sight of claim 6, wherein the first and second reticle elements are etched onto the first and second surfaces.

15. The direct view telescope sight of claim 6, wherein the first reticle element comprises a reflective electronic display disposed adjacent to the first surface and the second reticle element comprises an etched reticle.

16. A method of magnifying an object image with a direct view telescopic sight, the method comprising:

focusing substantially collimated light of the object image to one focal plane with an objective lens assembly, wherein the one focal plane is one focal plane of a plurality of focal planes;

substantially re-collimating the object image focused onto the one focal plane with an eyepiece assembly;

inverting the object image with a prism erector assembly positioned in an optical path between the objective lens assembly and the eyepiece assembly, wherein the prism erector assembly includes first and second prism elements through which the optical path passes, and wherein surfaces of the first and second prism elements are each associated with a different focal plane of the plurality of focal planes; and

combining a first reticle onto the object image with a first reticle element disposed on a first surface of one of the first or second prism elements or disposed immediately adjacent to the first surface without an intervening element having optical power, wherein the first reticle element is associated with a first focal plane of the plurality of focal planes,

wherein the object image is brought into focus at only the one focal plane along the optical path between the objective lens and eyepiece assemblies at a given time, and wherein the one focal plane is selected to be coincident with the first focal plane of the plurality of focal planes at the given time.

17. The method of claim 16, further comprising:

changing a zoom setting of the direct view telescopic sight by adjusting focal lengths of first and second adjustable lenses disposed within the objective lens assembly to change the field of view (“

FOV”

) of the objective lens assembly while holding the one focal plane at the first focal plane and maintaining a size of the image focused onto the one focal plane constant.

18. The method of claim 17, further comprising:

changing an axial position of a limiting aperture when changing the zoom setting while maintaining constant locations for each of the first and second adjustable lenses when changing the zoom setting.

19. The method of claim 17, wherein the first reticle element comprises a reflective electronic display, the method further comprising:

adjusting a size of the first reticle displayed by the reflective electronic display while changing the FOV to maintain a constant angular meaning of marks within the first reticle relative to the object image from one zoom setting to a next zoom setting.

20. The method of claim 19, further comprising:

changing a type of the first reticle based upon the zoom setting.

21. The method of claim 16, further comprising:

changing a zoom setting of the direct view telescopic sight by adjusting a first focal length of a first adjustable lens disposed within the objective lens assembly and adjusting a second focal length of a second adjustable lens disposed within the eyepiece assembly to change a position of the one focal plane to be coincident with a different focal plane of the plurality of focal planes.

22. The method of claim 21, wherein changing the position of the one focal plane within the prism erector assembly comprises adjusting the one focal plane from being coincident with the first focal plane to a second focal plane of the plurality of focal planes.

23. The method of claim 22, further comprising:

superimposing a second reticle onto the object image with a second reticle element disposed on or adjacent to the second surface when the one focal plane is coincident with the second focal plane,

wherein the second reticle is different from the first reticle,

wherein the first reticle is not viewable from the eyepiece assembly when the one focal plane is coincident with the second focal plane and the second reticle is not viewable from the eyepiece assembly when the one focal plane is coincident with the first focal plane.