Stereoscopic projector with rotating segmented disk
View Patent ↗A stereoscopic digital image projecting system has a light source system providing polarized illumination having a first polarization state and a beam splitting system with a rotating segmented disk in the illumination, alternately generating first and second light beams, the rotating segmented disk having outer segments alternately transmissive and non-transmissive and inner segments radially aligned with the outer segments and alternately reflective and transmissive. A polarization rotator in a path of either the first or second light beam rotates the first polarization state to a second state orthogonal to the first. A combining system combines the first and second light beams into a combined light beam. A spatial light modulator modulates the combined light beam in a manner consistent with stereoscopic image data to form first and second modulated images having substantially orthogonal polarization states. Projection optics project the modulated images onto a display surface.
1. A stereoscopic digital image projecting system comprising:
a light source system energizable to provide polarized illumination having a first polarization state;
a beam splitting system comprising a rotating segmented disk disposed in a path of the polarized illumination and alternately generating first and second light beams from the polarized illumination, the rotating segmented disk comprising outer segments alternately transmissive and non-transmissive and inner segments radially aligned with the outer segments and each alternately reflective and transmissive, wherein the inner reflective segments correspond with the outer transmissive segments;
a polarization rotator positioned in a path of either the first or second light beam and rotating the first polarization state to a second polarization state orthogonal or substantially orthogonal to the first polarization state;
a combining system combining the first and second light beams into a combined light beam;
a spatial light modulator modulating the combined light beam in a manner consistent with stereoscopic image data to form a first modulated image from illumination in the combined light beam having the first polarization state and to form a second modulated image from illumination in the combined light beam having the second polarization state; and
projection optics configured to project the first and second modulated images onto a display surface.
2. The system of claim 1 , wherein the first light beam is generated when the polarized illumination is transmitted through a transmissive inner segment and the second light beam is generated when the polarized illumination is reflected from a reflective inner segment and transmitted through a transmissive outer segment.
3. The system of claim 2 , further including a converging optical element that converges the polarized illumination to a reduced light beam diameter at the beam splitting system.
4. The system of claim 3 , wherein the converging optical element is a lens or a mirror.
5. The system of claim 3 , wherein the converging optical element converges the polarized illumination such that a minimum beam diameter for the second light beam occurs at a point following its reflection from the reflective inner segment and prior to its transmission through the transmissive outer segment.
6. The system of claim 5 , wherein a first beam diameter of the first light beam when it passes through the transmissive inner segment is equal or substantially equal to a second beam diameter of the second light beam when it passes through the transmissive outer segment.
7. The system of claim 2 , wherein the beam splitting system further comprises a mirror that directs light reflected from the inner reflective segments through the outer transmissive segments.
8. The system of claim 7 , wherein the mirror is angled appropriately to converge the first light beam and the second light beam thereby functioning as a component of the combining system.
9. The system of claim 8 , wherein the first light beam and the second light beam are converged at the modulator.
10. The system of claim 8 , wherein the first light beam and the second light beam are converged onto an integrating bar or a lenslet array.
11. The system of claim 7 , wherein the mirror is a reflective retarder that performs the function of the polarization rotator.
12. The system of claim 1 , wherein the outer non-transmissive segments are light absorbing.
13. The system of claim 1 , wherein the outer non-transmissive segments are reflective.
14. The system of claim 13 , wherein a back surface of the outer reflective segments is light absorbing, scattering, or both absorbing and scattering.
15. The system of claim 1 , wherein the rotating segmented disk comprises only two outer segments and two inner segments.
16. The system of claim 1 , wherein at least a portion of the rotating segmented disk is textured in a manner that reduces coherence artifacts.
17. The system of claim 1 , wherein the combining system comprises a polarizing beam splitter, an integrating bar, or a lenslet array.
18. The system of claim 1 , wherein the polarization rotator comprises a half-wave plate or a reflective retarder or an electronic retarder.
19. The system of claim 1 , wherein the combining system comprises a polarization beam combiner.
20. The system of claim 19 , wherein the polarization beam combiner is a thin film plate, thin film cube, wire grid, or Brewster angle element.