Beam splitter and optical imaging systems incorporating same

• US 20060180744A1
• Filed: 02/08/2006
• Published: 08/17/2006
• Est. Priority Date: 01/12/2005
• Status: Active Grant

• Current Assignee: Nantong Schmidt Opto-Electrical Technology Co. Ltd.
• Original Assignee: Pacific Telescope Corp.
• Inventors: Shen, Dar Tson
• Granted Patent: US 7,369,315 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: G02B 23/04 for the purpose of beam splitting or combining, e.g. fitted with eyepieces for more than one observer G02B23/10 takes precedence
• CPC Class Codes: G02B 23/14 Viewfinders for photographic apparatus G03B13/02
• CPC Class Codes: G02B 27/108 for sampling a portion of a beam or combining a small beam in a larger one, e.g. wherein the area ratio or power ratio of the divided beams significantly differs from unity, without spectral selectivity
• CPC Class Codes: G02B 27/143 using macroscopically faceted or segmented reflective surfaces
• CPC Class Codes: G02B 27/16 used as aids for focusing
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08

Abstract

An optical imaging system comprises an input optical system, which collects light from a scene and directs the light onto an input optical path. The optical imaging system also comprises a beam splitter, which is moveable to a beam-splitting position where the beam splitter intercepts the light on the input optical path and a non-beam-splitting position where the beam splitter is located outside of the input optical path. The beam splitter comprises a body penetrated by an aperture and a reflective surface surrounding the aperture. When the beam splitter is located in the beam-splitting position, a portion of the light in the optical path is transmitted through the aperture and a portion of the light in the optical path is reflected from the reflective surface. Both the reflected portion of the light and the transmitted portion of the light are capable of reproducing images of the scene at their respective focal points. Introduction of the beam splitter into the optical path and withdrawal of the beam splitter from the optical path do not change the optical path length of the imaging system.

Claims

1. A beam splitter positionable to intercept light in an optical path, the beam splitter comprising:

a body penetrated by an aperture; and

a reflective surface surrounding the aperture,

wherein a transmitted portion of the light in the optical path is transmitted through the aperture and a reflected portion of the light in the optical path is reflected from the reflective surface.

2. A beam splitter according to claim 1 wherein the body comprises one or more edges which define the aperture and at least one portion each edge is beveled with respect to a plane of the reflective surface.

3. A beam splitter according to claim 2 wherein an angle between the at least one portion and the plane of the reflective surface is 45°

.

4. A beam splitter according to claim 1 wherein the body comprises one or more edges which define the aperture and, when the beam splitter is positioned to intercept the light in the optical path, the one or more edges are parallel with an optical axis of the optical path and the reflective surface forms a non-orthogonal angle with the optical axis of the optical path.

5. A beam splitter according to claim 4 wherein the non-orthogonal angle between a plane of the reflective surface and the optical axis of the optical path is 45°

.

6. A beam splitter according to claim 4 wherein when the beam splitter is positioned to intercept the light in the optical path, the optical axis of the optical path is aligned with a central axis of the aperture.

7. A beam splitter according to claim 4 wherein an optical reflectance of the reflective surface is greater than 80% for light having wavelengths over at least 80% of a range of 400-700 nanometers.

8. A beam splitter according to claim 4 wherein a ratio of a cross-sectional area of the aperture to a surface area of the reflective surface is in a range of 1:

20 (5%) to 1;

3 (33%).

9. An optical imaging system comprising a beam splitter according to claim 1 and an input optical system for collecting light from a scene and directing the light from the scene onto the optical path.

10. An optical imaging system according to claim 9 wherein the transmitted portion of the light forms a first image of the scene and wherein the reflected portion of the light forms a second image of the scene.

11. An optical imaging system according to claim 10 wherein the input optical system comprises at least one of:

an objective lens system, a concave mirror; and

a collimating lens system.

12. An optical imaging system according to claim 10 wherein the input optical system is operative to cause the light on the optical path to converge.

13. An optical imaging system according to claim 12 wherein the transmitted portion of the light converges to form the first image of the scene at a first focal plane incorporating a first focal point and the reflected portion of the light converges to form the second image of the scene at a second focal plane incorporating a second focal point.

14. An optical imaging system according to claim 13 wherein a first optical path length from the input optical system to the first focal point is substantially the same as a second optical path length from the input optical system to the beam splitter and from the beam splitter to the second focal point.

15. An optical imaging system according to claim 14 comprising a mechanism for selectively moving the beam splitter to a non-beam-splitting position outside of the optical path.

16. An optical imaging system according to claim 15 wherein, when the beam splitter is in the non-beam-splitting position, substantially all of the light directed onto the optical path by the input optical system converges to form a third image of the scene at the first focal plane.

17. An optical imaging system according to claim 13 comprising a digital imaging system located to sense at least one of the first and second images and to provide digital data representing the sensed image.

18. An optical imaging system according to claim 13 comprising an eyepiece optical system located to receive at least one of the first and second images and to provide a reproduced image to an eyepiece.

19. An optical imaging system according to claim 16 comprising a digital imaging system having a single focal length and located to sense the first image and to provide digital data representing the first image when the beam splitter is positioned to intercept light in the optical path and to sense the third image and to provide digital data representing the third image when the beam splitter is in the non-beam-splitting position.

20. An optical imaging system according to claim 16 comprising an eyepiece optical system having a single focal length and located to receive the first image when the beam splitter is positioned to intercept light in the optical path and to receive the third image when the beam splitter is in the non-beam-splitting position and to provide a reproduced image to an eyepiece.

21. An optical imaging system according to claim 18 comprising an erecting prism system interposed between the input optical system and the eyepiece optical system.

22. An optical imaging system according to claim 20 comprising an erecting prism system interposed between the input optical system and the eyepiece optical system.

23. An optical imaging system according to claim 10 wherein the reflective surface comprises a front surface mirror.

24. An optical imaging system comprising:

a primary input optical system operative to collect light from a scene and to direct the light onto an input optical path; and

a beam splitter which is moveable to a beam-splitting position where the beam splitter intercepts the light on the input optical path and a non-beam-splitting position where the beam splitter is located outside of the input optical path;

wherein the beam splitter comprises a body penetrated by an aperture and a reflective surface surrounding the aperture and wherein, when the beam splitter is located in the beam-splitting position, a transmitted portion of the light in the optical path is transmitted through the aperture and a reflected portion of the light in the optical path is reflected from the reflective surface.

25. An optical imaging system according to claim 24 wherein the beam splitter body comprises one or more edges which define the aperture and at least a portion of each edge is beveled with respect to a plane of the reflective surface.

26. An optical imaging system according to claim 24 wherein when the beam splitter is in the beam-splitting position, the one or more edges are parallel with an optical axis of the input optical path and a plane of the reflective surface forms a non-orthogonal angle with the optical axis of the input optical path.

27. An optical imaging system according to claim 26 wherein when the beam splitter is in the beam-splitting position, the optical axis of the input optical path is aligned with a central axis of the aperture.

28. An optical imaging system according to claim 26 wherein the input optical system causes light on the input optical path to converge such that, when the beam splitter is in the beam-splitting position, the transmitted portion of the light forms a first image of the scene at a first focal plane incorporating a first focal point and the reflected portion of the light forms a second image of the scene at a second focal plane incorporating a second focal point and, when the beam splitter is in the non-beam-splitting position, the light on the input optical path forms a third image of the scene at a third focal plane incorporating a third focal point.

29. An optical imaging system according to claim 28 wherein the first and third focal planes are the same.

30. An optical imaging system according to claim 28 wherein a first optical path length from the input optical system to the first focal point, a second optical path length from the input optical system to the beam splitter and from the beam splitter to the second focal point and a third optical path length from the input optical system to the third focal point are all substantially the same.

31. An optical imaging system according to claim 30 comprising a digital imaging system located to sense at least one of the first and second images and to provide digital image data representing the sensed image.

32. An optical imaging system according to claim 31 comprising an eyepiece optical system located to receive one of the first and second images and to provide a reproduced image to an eyepiece at the same time that the digital imaging system is sensing and providing digital image data representing the other one of the first and second images.

33. An optical imaging system according to claim 28 comprising a digital imaging system having a single focal length located to sense and provide digital image data representing the first image when the beam splitter is in the beam-splitting position and to sense and provide digital image data representing the third image when the beam splitter is in the non-beam-splitting position.

34. An optical imaging system according to claim 33 comprising an eyepiece optical system located to receive the second image when the beam splitter is in the beam-splitting position and to provide a reproduced image to an eyepiece.

35. An optical imaging system according to claim 28 comprising an eyepiece optical system having a single focal length located to receive the first image when the beam splitter is in the beam-splitting position and to receive the third image when the beam splitter is in the non-beam-splitting position and to provide a reproduced image to an eyepiece.

36. An optical imaging system according to claim 35 comprising a digital imaging system located to sense and provide digital image data representing the second image when the beam splitter is in the beam-splitting position.

37. An optical imaging system according to claim 28 comprising a secondary input optical system operative to collect light from the scene, to direct the collected light onto a secondary optical path and to cause the light on the secondary optical path to converge to form a fourth image of the scene at a fourth focal plane incorporating a fourth focal point.

38. An optical imaging system according to claim 37 wherein the fourth focal plane and the second focal plane are the same.

39. An optical imaging system according to claim 38 comprising a movable member which is moveable between a first position where the member blocks light on the secondary optical path when the beam splitter is in the beam-splitting position and a second position where the member is located outside of the secondary optical path when the beam splitter is in the non-beam-splitting position.

40. An optical imaging system according to claim 39 wherein the moveable member comprises a reflective surface and wherein, when the moveable member is located in the first position, the reflective surface of the member further reflects the reflected portion of the light which has already been reflected by the beam splitter.

41. A method for providing images of a scene in more than one location, the method comprising:

collecting light from the scene and directing the light onto an optical path;

causing the light in the optical path to converge toward a first focal point to provide a first image of the scene at the first focal point;

when an image of the scene is required at a second location;

moving an apertured reflective surface into the optical path;

causing a portion of the light in the optical path to reflect from the reflective surface and to converge toward a second focal point to provide a second image of the scene at the second focal point; and

allowing a portion of the light in the optical path to pass through the aperture in the reflective surface and to converge toward the first focal point to provide a third image of the scene at the first focal point.