Real imaging system with reduced ghost imaging

• US 20030147145A1
• Filed: 01/24/2003
• Published: 08/07/2003
• Est. Priority Date: 04/27/1999
• Status: Active Grant

• Current Assignee: Optical Products Development Corporation
• Original Assignee: Optical Products Development Corporation
• Inventors: Westort, Kenneth S., Robinson, Douglas L.
• Granted Patent: US 6,798,579 B2
• Time in Patent Office: Days
• US Class Current: 359/649
• CPC Class Codes: G02B 17/0621 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0694 with variable magnification or multiple imaging planes, including multispectral systems systems with only refractive elements G02B15/14
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: H04M 1/72442 for playing music files
• CPC Class Codes: H04N 9/12 Picture reproducers H04N9/11 takes precedence

Abstract

A real image display system includes a primary image source for projecting a primary image from the start of a primary light path to an end of the primary light path at which the primary image is viewable, two reflectors positioned in the primary light path between the primary image source and the projected real image, a circular polarizer for circularly polarizing a light beam positioned in the primary light path between the mirror and real image, whereby outside light entering the system is substantially blocked before exiting the system, thereby substantially eliminating ghost image formation caused by outside light sources.

Claims

1. A real image display system comprising:

a) a real imaging system for projecting a real image, said imaging system incorporating curved reflectors, at least one of which comprises an aspheric surface of revolution; and

b) a circular polarizing window or a neutral density filter window.

2. The real image display system of claim 1, wherein said neutral density filter window is between 15% and 40% absorption.

3. The real image display system of claim 2, wherein said neutral density filter has an antireflective coating on one or both surfaces thereof.

4. The real image display system of claim 1, wherein said circular polarizing window comprises a linear polarizing film and quarter wave plate, said linear polarizing film facing said real image, and said quarter wave plate facing at least one of said curved reflectors.

5. The real image display system of claim 4, wherein said circular polarizing window is secured to a clear substrate or between two clear substrates.

6. The real image display system of claim 4, wherein said circular polarizing window includes an anti-reflective coating on one or both surfaces thereof.

7. The real image display system of claim 4, wherein said real imaging system does not utilize a tilted beamsplitter between said curved reflector and said real image, such that said real image is not reflected from a beamsplitter surface.

8. A real image projection system, comprising:

a) a visual staging station defining a space for viewing images from a vantage point along a viewing axis;

b) at least two curved optics of the conical family of curves, at least one of said optics comprising an aspherical surface of revolution, wherein said curved optics are arranged such that an object positioned substantially at or near a focal point of one of said curved optics forms a real image positioned substantially at or near a focal point of another of said curved optics, and said real image is projected along said viewing axis and appears as a floating image when viewed from said visual staging station; and

c) a circular polarizing window or a neutral density filter window.

9. The real image display system of claim 8, wherein said neutral density filter window is between 15% and 40% absorption.

10. The real image display system of claim 9, wherein said neutral density filter has an anti-reflective coating on one or both surfaces thereof.

11. The real image display system of claim 8, wherein said circular polarizing window comprises a linear polarizing film and quarter wave plate, said linear polarizing film facing said real image, and said quarter wave plate facing at least one of said curved reflectors.

12. The real image display system of claim 11, wherein said circular polarizing window is secured to a clear substrate or between two clear substrates.

13. The real image display system of claim 9, wherein said circular polarizing window includes an anti-reflective coating on one or both surfaces thereof.

14. The real image display system of claim 9, wherein said real imaging system does not utilize a tilted beamsplitter between said curved reflector and said real image, such that said real image is not reflected from a beamsplitter surface.

15. A real image projection system, comprising:

a) at least one curved reflector for projecting a real image, said reflector being positioned in a tilted configuration, wherein an optical axis of said reflector is not coincident with a viewing axis, and a beampath between a target source and said curved reflector neither passes through nor reflects off of a beamsplitter; and

b) a circular polarizing window or a neutral density filter window.

16. The real image display system of claim 15, wherein said neutral density filter window is between 15% and 40% absorption.

17. The real image display system of claim 16, wherein said neutral density filter has an anti-reflective coating on one or both surfaces thereof.

18. The real image display system of claim 15, wherein said circular polarizing window comprises a linear polarizing film and quarter wave plate, said linear polarizing film facing said real image, and said quarter wave plate facing at least one of said curved reflectors.

19. The real image display system of claim 18, wherein said circular polarizing window is secured to a clear substrate or between two clear substrates.

20. The real image display system of claim 19, wherein said circular polarizing window includes an anti-reflective coating on one or both surfaces thereof.