Stereoscopic projection system employing spatial multiplexing at an intermediate image plane
Projection systems and methods for providing stereoscopic images viewed through passive polarizing eyewear. The systems relate to projectors that create left and right eye images simultaneously and often as side-by-side images on the image modulator. The systems act to superimpose the spatially separated images on a projection screen with alternate polarization states. The embodiments are best suited to liquid crystal polarization based projection systems and use advanced polarization control.
1. A stereoscopic projection system, comprising:
a relay lens subsystem operable to receive a stereoscopic image frame from a projection subsystem along an input light path and convey the stereoscopic image frame to an intermediate image plane, the stereoscopic image frame having first image area light and second image area light;
a light splitting subsystem operable to receive the stereoscopic image frame at the intermediate image plane and split the first image area light from the second image area light, to direct the first image area light on a first image light path, and to direct the second image area light on a second image light path;
a light combining subsystem operable to combine the first and second image area light, wherein the first image area light that is output from the light combining subsystem has a polarization state orthogonal to the second image area light; and
a projection lens subsystem operable to direct the first and second image area light toward a screen.
2. The stereoscopic projection system of claim 1 , wherein the light combining subsystem comprises a polarization beam splitter (PBS).
3. The stereoscopic projection system of claim 1 wherein the projection lens subsystem comprises a single projection lens.
4. The stereoscopic projection system of claim 1 , further comprising a liquid crystal (LC) projector.
5. The stereoscopic projection system of claim 4 , further comprising a matched waveplate located on the input light path before the relay lens subsystem, the matched waveplate being substantially dispersion matched to a waveplate within the LC projector.
6. The stereoscopic projection system of claim 4 , further comprising a matched waveplate located on the intermediate light path after the relay lens subsystem, the matched waveplate being substantially dispersion matched to a waveplate within the LC projector.
7. The stereoscopic projection system of claim 1 , further comprising:
a wavelength selective polarization filter located on one of the input light path and intermediate light path.
8. The stereoscopic projection system of claim 1 , further comprising a quarter wave plate located on an output light path.
9. The stereoscopic projection system of claim 1 , wherein the light splitting subsystem comprises first and second mirrors.
10. The stereoscopic projection system of claim 1 , wherein the light splitting subsystem comprises one of a total internal reflection prism, a mirrored prism, and a pair of total internal reflection prisms.
11. The stereoscopic projection system of claim 1 , wherein the projection lens subsystem comprises a polarization beam splitter (PBS) and a single projection lens;
wherein the PBS is operable to combine the first and second image area light;
wherein the single projection lens is operable to project the combined first and second image area light toward the screen; and
wherein the first and second image area light substantially overlap on the screen.
12. The stereoscopic projection system of claim 1 , wherein the stereoscopic image frame is conveyed to the intermediate image plane via a light directing element.
13. The stereoscopic projection system of claim 12 , wherein the light directing element comprises one of a mirror and a prism.
14. A projection system operable to selectively project stereoscopic and non-stereoscopic projection modes, comprising:
a relay lens subsystem operable to receive input light from a projection subsystem and convey the input light toward an intermediate light path;
a stereoscopic module operable to receive the light from the intermediate light path and process the light for stereoscopic projection of left and right eye images having orthogonal polarization states;
a non-stereoscopic module operable to receive the light from the intermediate light path;
a projection lens subsystem operable to focus light from the stereoscopic module or the non-stereoscopic module toward a screen; and
wherein when in a stereoscopic projection mode, the stereoscopic module is located in the intermediate light path, and wherein when in a non-stereoscopic projection mode, the non-stereoscopic module is located in the intermediate light path.
15. The projection system of claim 14 , further comprising a selector for selecting between the stereoscopic mode and the non-stereoscopic mode.
16. The projection system of claim 14 , further comprising a mechanism operable to selectively locate the stereoscopic module into the intermediate light path when in the stereoscopic mode, and locate the non-stereoscopic module into the intermediate light path when in the non-stereoscopic mode.
17. The projection system of claim 16 , further comprising an actuator operable to move the mechanism between the stereoscopic mode and the non-stereoscopic mode.
18. The projection system of claim 14 , further comprising a light directing element located after the relay lens subsystem, operable to direct light toward on the intermediate light path.
19. The projection system of claim 18 , wherein the light directing element is selected from the group comprising a mirror, and a prism.
20. The projection system of claim 14 , wherein the stereoscopic module comprises:
a light splitting subsystem operable to:
receive a stereoscopic image frame having first and second image area light at an intermediate image plane,
split the first image area light from the second image area light,
to direct the first image area light on a first image light path, and
to direct the second image area light on a second image light path; and
a light combining subsystem operable to combine the first and second image area light, wherein the first image area light that is output from the light combining subsystem has a polarization state orthogonal to the second image area light.
21. The stereoscopic projection system of claim 14 , further comprising a liquid crystal (LC) projector.
22. The stereoscopic projection system of claim 14 , further comprising a quarter wave plate located on an output light path.