Theta-parallax-only (TPO) displays

1. A 3-D display comprising:

a rotating optical diffuser for displaying 3-D parallax images in specific substantially unidirectional viewing zones as the rotating optical diffuser rotates; and

a projector for projecting images through the rotating optical diffuser;

wherein the rotating optical diffuser is located to rotate about an axis that is substantially normal to a display surface.

2. The 3-D display of claim 1 wherein the rotating optical diffuser is located to rotate in a plane parallel to a flat display surface plane of a flat display.

3. The 3-D display of claim 1 wherein the rotating optical diffuser further comprises:

a light guide collimator.

4. The 3-D display of claim 1 wherein the rotating optical diffuser is rotated by a rotatable cakepan and wherein the cakepan is connected to a motor which turns the cakepan.

5. The 3-D display of claim 4 wherein at least one relay mirror is located in the cakepan for relaying images from the projector to the rotating optical diffuser.

6. The 3-D display of claim 1 wherein the projector is a digital micromirror device (DMD).

7. The 3-D display of claim 1 wherein the rotating optical diffuser propagates a bundle of rays with a 2-D cross section and wherein the bundle of rays are pitched at a desired display angle.

8. The 3-D display of claim 1 wherein the rotating optical diffuser is structured so that a bundle of projected rays sweep out a conical volume to form a 3-D image.

9. The 3-D display of claim 1 wherein the rotating optical diffuser is structured to propagate a bundle of rays with a 2-D cross section so that the bundle of rays form a private image viewable only from one viewing position.

10. The 3-D display of claim 1 wherein the rotating optical diffuser comprises a light shaping diffuser having a collimating light steering layer located beneath the light shaping diffuser and also having a first imaging surface located beneath the collimating light steering layer to receive images from the projector.

11. The 3-D display of claim 10 wherein the collimating light steering layer is a collimating grid located beneath the light shaping diffuser and collimates light to be pitched at an angle.

12. The 3-D display of claim 1 wherein the rotating optical diffuser comprises a louver having a diffraction grating located beneath the louver and a Fresnel lens located beneath the diffraction grating.

13. The 3-D display of claim 1 wherein the rotating optical diffuser comprises a Fresnel lens.

14. The 3-D display of claim 1 wherein the rotating optical diffuser comprises an off axis Fresnel lens.