Volumetric Three-Dimensional Display System
The invention features a volumetric display system. A light beam representing an image is provided from a stationary source. A projection screen is rotated, relative to the stationary source, about a rotation axis. The light beam is projected onto the projection screen at a non-normal angle of incidence. The light beam is manipulated to reduce distortion in the image caused by projection of the light beam onto the projection screen.
1 . A system comprising:
a first optical assembly configured to provide a light beam representing an image, the first optical assembly being disposed on a first support structure;
a motor coupled to the first support structure and configured to rotate a second support structure, relative to the first support structure, about a rotation axis; and
a second optical assembly that includes one or more optical elements configured to manipulate the light beam to reduce distortion in the image caused by projection of the light beam onto a projection screen at a non-normal angle of incidence, the second optical assembly being disposed on the second support structure.
2 . The system of claim 1 , further comprising an image data and illumination module configured to provide an unmodulated light beam and image data defining the image, wherein the first optical assembly is configured to generate the light beam by spatially modulating the unmodulated light beam according to the image data.
3 . The system of claim 1 , further comprising a projection screen disposed on the second support structure and positioned to receive a manipulated light beam from the second optical assembly, the projection screen having a substantially flat surface that is substantially parallel to the rotation axis.
4 . The system of claim 2 , wherein the second optical assembly includes a mirror disposed along the rotation axis to receive the light beam from the second optical assembly.
5 . The system of claim 4 , wherein the first optical assembly is configured to image the spatially modulated light beam to an intermediate image plane, where the intermediate image plane is substantially perpendicular to the rotation axis and less than about two centimeters from the mirror.
6 . The system of claim 2 , wherein the first optical assembly is further configured to:
split the unmodulated light beam received from the image data and illumination module into a plurality of component beams of different color;
modulate each component beam according to corresponding image data; and
recombine the modulated component beams into in a combined light beam representing a multi-color image.
7 . The system of claim 6 , wherein the first optical assembly includes a plurality of optical elements arranged to support forward light paths from locations at which the component beams are modulated to a mirror and reverse light paths from the mirror to an output of the first optical assembly, where the forward light paths are arranged with respect to the reverse light paths to enable the reverse path to at least partially compensate for aberrations produced by the forward path.
8 . The system of claim 7 , wherein the reverse path is arranged to substantially compensate for spherical aberration produced by the forward path.
9 . The system of claim 8 , wherein the reverse path is arranged to reduce spherical aberration produced by the forward path to less than one wavelength.
10 . The system of claim 6 , wherein the first optical assembly includes at least one optical element configured to reduce chromatic aberration induced by other optical elements of the first optical assembly.
11 . The system of claim 1 , wherein the second optical assembly is configured to manipulate the light beam to reduce one or more of keystone distortion, pincushion distortion, and barrel distortion.
12 . The system of claim 1 , wherein the second optical assembly is configured to manipulate the light beam to compress the transverse profile of the light beam along a first transverse direction relative to a second perpendicular transverse direction.
13 . The system of claim 12 , wherein the amount of relative compression is based on an angle at which the image is to be projected onto the projection screen.
14 . The system of claim 1 , wherein the second optical assembly is configured to provide a tilted focal plane according to the angle at which the image is projected onto the projection screen.
15 . The system of claim 1 , wherein the second optical assembly is configured to manipulate the light beam to provide a large depth of focus at the projection screen.
16 . The system of claim 15 , wherein the depth of focus is larger than the size of the projected image multiplied by the sine of the angle of incidence at the projection screen.
17 . The system of claim 1 , wherein the second optical assembly is further configured to manipulate the light beam to substantially flatten the field of the image represented by the light beam.
18 . The system of claim 1 , wherein the second optical assembly consists essentially of reflective optical elements including at least one curved mirror.
19 . The system of claim 18 , wherein the second optical assembly includes at least one mirror having a negative curvature characterized by a concave curvature along a first cross-section and a convex curvature along an orthogonal cross-section.
20 . The system of claim 19 , wherein the second optical assembly includes one mirror having a negative curvature, at least one mirror having a positive convex curvature, and at least one mirror having a positive concave curvature.
21 . The system of claim 2 , wherein the second optical assembly is configured to magnify the image when projected onto a projection screen, relative to the size of the image when spatially modulated onto the light beam by the first optical assembly.
22 . The system of claim 21 , wherein the magnification is at least a factor of 10.
23 . The system of claim 2 , wherein the image data and illumination module is configured to process the image data to reduce residual distortion not corrected by the one or more optical elements of the second optical assembly.
24 . The system of claim 1 , wherein the second optical assembly is configured to reduce distortion in the image such that the size of any residual distortion is less than about 5% of the size of the image.
25 . The system of claim 1 , wherein the second optical assembly is configured to reduce distortion in the image such that any point in the projected image is displaced from its respective location in the image provided by the first optical assembly to less than 5% relative to the size of the projected image.
26 . The system of claim 2 , wherein the image data and illumination module is configured to process the image data to reduce distortion in the image such that the size of any residual distortion not corrected by the combined effect of the processing and the one or more optical elements of the second optical assembly is less than 2% of the size of the image.
27 . The system of claim 2 , wherein the image data and illumination module is configured to process the image data to reduce distortion in the image such that the size of any residual distortion not corrected by the combined effect of the processing and the one or more optical elements of the second optical assembly is less than the size of two pixels of the image.
28 . The system of claim 1 , wherein the first optical assembly and the second optical assembly include one or more adjustable components to project the image onto the projection screen in-focus and approximately centered on the projection screen.
29 . A method, comprising:
providing a light beam representing an image from a stationary source;
rotating a projection screen, relative to the stationary source, about a rotation axis;
projecting the light beam onto the projection screen at a non-normal angle of incidence; and
manipulating the light beam to reduce distortion in the image caused by projection of the light beam onto the projection screen.
30 . The method of claim 29 , further comprising providing an unmodulated light beam and image data defining the image, wherein the light beam representing the image is generated by spatially modulating the unmodulated light beam according to the image data.