Compact optical see-through head-mounted display with occlusion support

• US 7,639,208 B1
• Filed: 05/13/2005
• Issued: 12/29/2009
• Est. Priority Date: 05/21/2004
• Status: Expired due to Fees

• Current Assignee: University of Central Florida (State University System of Florida)
• Original Assignee: University of Central Florida Research Foundation Inc. (State University System of Florida)
• Inventors: Cakmakci, Ozan, Ha, Yonggang, Rolland, Jannick
• Primary Examiner(s): Tran, Henry N
• Assistant Examiner(s): PHAM, VIET DAVID
• Application Number:
  US11/129,620
• Time in Patent Office: 1,691 Days
• Field of Search: 345/8, 345/9, 345/204, 359/630, 359/632
• US Class Current: 345/8
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/1066 for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G09G 2340/12 Overlay of images, i.e. displayed pixel being the result of switching between the corresponding input pixels
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT

Abstract

An optical system, apparatus and method are capable of mutual occlusions. The core of the system is a spatial light modulator (SLM) which allows users to block or pass certain parts of a scene which is viewed through the head worn display. An objective lens images the scene onto the SLM and the modulated image is mapped back to the original scene via an eyepiece. The invention combines computer-generated imagery with the modulated version of the scene to form the final image a user would see. The invention is a breakthrough in display hardware from a mobility (i.e. compactness), resolution, and speed, and is specifically, related to virtual objects being able to occlude real objects and real objects being able to occlude virtual objects.

Claims

1. A compact optical see-through system for a head worn display comprising:

an optical system having telecentricity in an intermediary space for selectively blocking and selectively passing selected portions of a scene from original scene images to produce a modulated output, the optical system including;

an objective lens having a focal point placed at an entrance pupil of the optical system to collect light from the original scene for imaging said original scene images onto said optical system;

a polarizing structure including a polarizer and an x-cube prism adjacent to the objective lens for polarizing the original scene from the objective lens to produce a polarized intermediary image;

a 3D real-time depth extraction system to determine an occlusion mask;

a spatial light modulator for receiving and modulating the polarization of the intermediary image to produce the modulated image based on the occlusion mask;

a microdisplay for displaying the virtual image, a light from the microdisplay being combined with a light from the spatial light modulator using the polarizing structure and reflecting the modulated intermediary image; and

an eyepiece with a focal point placed to form an exit pupil of the optical system for mapping said modulated image back to said original scene images for viewing by a user wearing said see-through head worn display, wherein said see-through head worn display displays virtual objects while occluding real objects and real objects occluding virtual objects.

2. The display of claim 1 wherein said spatial light modulator is a reflective spatial light modulator to increase compactness.

3. The display of claim 1 wherein said eyepiece is located approximately a front focal length away from said spatial light modulator for delivering a collimated image to said user.

4. The display of claim 1 wherein said compact optical see-through head worn display is one of a monocular, biocular, and binocular.

5. A compact optical display system having telecentricity in an intermediary space capable of mutual occlusions, the optical system consisting essentially of:

a lens having a focal point placed to form an entrance pupil of the optical system for collecting light from a scene, in a telecentric manner;

a polarizer adjacent to the lens for polarizing said light from said lens;

a prism adjacent to the polarizer;

an image source to provide a computer-generated image;

a reflective spatial light modulator adjacent to the prism for receiving and modulating said light from plural pixels of said scene on a pixel by pixel basis and said computer generated image to produce a modulated output to image a preferred specified field of view onto the spatial light modulator for selectively turning pixels on and off in the real world scene; and

an eyepiece having a focal point placed to form an exit pupil of the optical system for mapping said modulated output back to said scene, wherein a user views said output with a perception of indifference between said computer-generated image overlaid on said scene.

6. The display system of claim 5 wherein said lens includes:

a telecentric objective lens.

7. The display system of claim 5, wherein said prism includes:

one of a polarizing structure, an x-cube polarizing prism or a free standing wiregrid polarizing structure.

8. The display system of claim 5, wherein the image source comprises:

one of a micro display, a liquid crystal display and an OLED.

9. A method of occluding real objects with virtual objects in an optical see-through head mounted display, consisting essentially of the steps of:

combining a computer generated image from an image source with a modulated version of an original scene by an optical system having telecentricity in an intermediary space, comprising the steps of;

placing a focal point of an optical lens at an entrance pupil of the optical system;

collecting light from a scene, in a telecentric manner, by the optical lens to produce an inverted image of the scene;

polarizing said inverted image of said scene by a polarizer adjacent to the lens;

reflecting the polarized image by a prism to a reflective spatial light modulator;

modulating the polarized image of the scene reflected from the prism then reflecting the modulated image back to the prism; and

reflecting the modulated image by the prism to an exit pupil of the optical system;

placing a focal point of an eyepiece to form the exit pupil of the optical system; and

mapping the combined image by the eyepiece back onto said original scene with approximately a 1;

1 magnification and upright orientation to occlude real objects with virtual objects in an optical see-through system for a head mounted display.

10. The method of claim 9, wherein said combining step comprises:

imaging the original scene; and

selectively blocking and selectively passing a portion of said original scene to produce a modulated image.

11. The method of claim 10, wherein said imaging step comprises:

mapping the modulated image back to the original scene, wherein the display is useful for displaying virtual objects occluded with real objects.