Retroreflective light field display

1. A projected head mounted display system comprising:

a head mounted frame including at least one image projector arranged to project images out of and forward away from, said frame, said projector or projectors having an adjustable projected focal plane distance; at least one controller to vary the focal plane distance of an image scene in a sequence selected to simulate a light field for projected images reflected back from a retroreflective screen or retroreflective surface; and a retroreflective screen or retroreflective surface having an effectively high ratio of retroreflected rays to diffused reflected rays so as to return to the eyes of the wearer of said projected head mounted display system, said projected images from said forward projecting image projector or projectors over said adjustable focal plane distance range of said image scene; wherein said head mounted display further comprises a tracking module to track the movement and position of a user and provide tracking data to a computing element to produce computer generated images (CGI) of objects having positions or perceived focal plane distances aligned with one or more real objects in view of the user; wherein each of said at least one image projectors comprises an electrically adjustable optical element to modulate the focal plane distances through a sequence that matches the visual distances of the generated image to the user at a rate sufficient to merge images in the visual perception of the user to simulate a light field.

2. The head mounted display system of claim 1 , wherein each focal distance of the projected planes in the sequence is selected to achieve accommodation to vergence expected at said distance.

3. The head mounted display system of claim 1 , where said focal plane of each image is varied in a sequence having at least three different focal distances and a rate selected to appear to a user to be simultaneous.

4. The projected head mounted display system of claim 1 , wherein said electrically adjustable optical element comprises an electrically adjustable lens.

5. The projected head mounted display system of claim 1 , wherein said electrically adjustable lens comprise at least one of an electrowetting lens and a deformable lens element.

6. The projected head mounted display system of claim 1 , wherein said electrically adjustable optical element comprises an adjustable reflective element.

7. The projected head mounted display system of claim 6 , wherein said adjustable reflective element comprises a deformable mirror.

8. The projected head mounted display system of claim 1 , wherein said electrically adjustable optical element comprises one or more motorized lens elements.

9. The projected head mounted display system of claim 1 , wherein said electrically adjustable optical element comprises one or more controllable diffraction elements.

10. The projected head mounted display system of claim 1 , wherein said electrically adjustable optical element comprises one or more lens elements, said lens elements having an electrically controllable index of refraction.

11. The electrically adjustable optical element of claim 1 , wherein said electrically adjustable optical element comprises surface acoustic wave optics.

12. The projected head mounted display system of claim 1 wherein said head mounted display further comprises a tracking module to track the movement and position of a user and includes a module to precompensate said projected images for imperfections in said retroreflective surface based on angle of incidence data from said tracking module.

13. A method of displaying visual images with a plurality of focal planes comprising:

a) providing a head mounted frame with one or more image projectors arranged to project images out of and forward away from, said frame, said projector or projectors having an electrically adjustable focal plane distance of projected images;

b) providing a retroreflective screen or retroreflective surface, said retroreflective screen or retroreflective surface having an effectively high ratio of retroreflected rays to diffused reflected rays so as to display images over said adjustable focal plane distance, by return of projected images from said image projectors to the eyes of a user;

c) tracking the movement and position of a user and providing tracking data to a computing element to produce computer generated images (CGI) of objects having positions or perceived focal plane distances aligned with one or more real objects in view of the user; and

d) stepping the focal plane distances through a sequence that matches the visual distances of the generated image to the user at a rate sufficient to merge images in the visual perception of the user to simulate a light field.

14. The method of claim 13 , where said step of stepping through the focal plane is repeated for a plurality of computer generated images.

15. The method of claim 13 , further comprising correcting for projection lens chromatic aberration.

16. The method of claim 13 , wherein said providing includes providing two image projectors presenting stereo vision images to the user wherein the expected vergence for at least one part of said images presented at each focal plane distance converges at that plane.

17. The method of claim 13 , further comprising tracking at least one of the head position and eye position of said user.

18. The method of claim 17 , further comprising modifying said projected images to precompensate for imperfections in said retroreflective screen based on said one of the head position and eye position of said user.

19. The method of claim 16 , wherein the image is an augmented reality image.