Illumination systems

• US 20100238549A1
• Filed: 04/05/2010
• Published: 09/23/2010
• Est. Priority Date: 07/06/2004
• Status: Active Grant

• Current Assignee: RealD Incorporated
• Original Assignee: Real D
• Inventors: Robinson, Michael G.
• Granted Patent: US 7,944,612 B2
• Time in Patent Office: Days
• US Class Current: 359/495
• CPC Class Codes: G02B 27/102 for generating a colour image from monochromatic image signal sources
• CPC Class Codes: G02B 27/14 operating by reflection only
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/144 using partially transparent surfaces without spectral selectivity G02B27/147 takes precedence
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• CPC Class Codes: G02B 27/148 including stacked surfaces having at least one double-pass partially reflecting surface
• CPC Class Codes: G02B 27/149 using crossed beamsplitting surfaces, e.g. cross-dichroic cubes or X-cubes
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: Y10S 359/90 Methods
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

Described are illumination systems whereby light spectra from multiple LEDs of various colors can be combined and polarized with minimal components, while substantially reducing the losses for the combining and polarizing. The described systems and methods use polarizing beam splitters (PBSs) with retarder stack filters to combine color and split polarization for mixed light beams in one step, and to ultimately align the polarizations of the several colored light beams.

Claims

1. An illumination system for receiving first and second input light sources, the first and second input light sources comprising first and second colors, respectively, the illumination system comprising:

first and second polarizing beam splitters, the first polarizing beam splitter operable to receive the first input light source at a first input and the second polarizing beam splitter operable to receive the second input light source at a second input, the two polarizing beam splitters operable to split the two input light sources into first and second mixed lights and to output the first mixed light at a first output and the second mixed light at a second output; and

first and second optical filters adjacent to the first and second outputs, respectively, the first and second optical filters operable to convert polarization states of the two mixed lights.

2. An illumination system according to claim 1, wherein the first and second mixed lights each comprises first and second colors.

3. An illumination system according to claim 1, wherein the first polarizing beam splitter is operable to output the first mixed light at a first output and the second polarizing beam splitter is operable to output the second mixed light at a second output.

4. An illumination system according to claim 1, further comprising collimating elements along the optic paths of the first and second input light sources, the collimating elements operable to substantially homogenize the first and second input light sources.

5. An illumination system according to claim 4, wherein the collimating elements are reflective or refractive optical elements.

6. An illumination system according to claim 1, wherein each of the first and second input light sources is operable to provide substantially square outputs of light.

7. An illumination system according to claim 1, wherein the first and second optical filters are polarization color selective filters or retarder stack filters.

8. An illumination system according to claim 1, further comprising first and second optical components adjacent to the first and second polarizing beam splitters, respectively, the first and second optical components operable to substantially split or combine the first and second mixed lights and control polarizations accordingly.

9. An illumination system according to claim 8, wherein the first and second optical components are selected from the group consisting of a quarter-wave plate, a half-wave plate, a reflecting mirror, a dichroic beam combiner, a polarizing beam splitter, and a color select filter.

10. An illumination system according to claim 1, further comprising an optical lens adjacent to the two polarizing beam splitters, the optical lens operable to project the first and second mixed lights.

11. An illumination system according to claim 10, wherein the optical lens is selected from the group consisting of a collimating lens, a fly'"'"'s eye lens, a projection lens, and a combining lens.

12. A method for splitting first and second input light sources in an illumination system, the first and second input light sources comprising first and second colors, respectively, the method comprising:

providing first and second polarizing beam splitters;

receiving the first input light source at a first input with the first polarizing beam splitter;

receiving the second input light source at a second input with the second polarizing beam splitter;

splitting the first and second input light sources into first and second mixed lights with the first and second polarizing beam splitters;

outputting the first mixed light at a first output with the first polarizing beam splitter;

outputting the second mixed light at a second output with the second polarizing beam splitter;

providing first and second optical filters adjacent to the first and second outputs, respectively; and

converting polarization states of the first and second mixed lights with the first and second optical filters, respectively.

13. A method according to claim 12, further comprising substantially homogenizing the first and second input light sources with collimating elements along the optic paths of the first and second input light sources.

14. A method according to claim 12, further comprising substantially splitting or combining the first and second mixed lights with first and second optical components adjacent to the first and second polarizing beam splitters, respectively.

15. A method according to claim 12, further comprising projecting the first and second mixed lights with an optical lens adjacent to the first and second polarizing beam splitters.

16. An X-cube architecture for receiving first, second, and third input light sources, the first, second, and third input light sources comprising first, second, and third colors, respectively, the X-cube architecture comprising:

a dichroic splitter operable to receive the first input light source at a first input, the second input light source at a second input, and the third input light source at a third input, and to combine the three input light sources into a mixed light, and to output the mixed light at an output; and

an optical filter adjacent to the output, the optical filter operable to convert polarization states of the mixed light.

17. An X-cube architecture according to claim 16, wherein the mixed light comprises first, second, and third colors.

18. An X-cube architecture according to claim 16, wherein the optical filter is a polarization color selective filter or a retarder stack filter.

19. An X-cube architecture according to claim 16, further comprising a polarizing element adjacent to the optical filter, the polarizing element operable to convert a polarization state of the mixed light.

20. An X-cube architecture according to claim 19, wherein the polarizing element is an s-polarizer or a p-polarizer.