Color imaging systems and methods

• US 6,899,430 B2
• Filed: 12/15/2000
• Issued: 05/31/2005
• Est. Priority Date: 04/07/1995
• Status: Expired due to Fees

• Current Assignee: RealD Incorporated
• Original Assignee: ColorLink, Incorporated (RealD Incorporated)
• Inventors: Johnson, Kristina M., Sharp, Gary D.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/736,135
• Publication Number:
  US 20010000971A1
• Time in Patent Office: 1,628 Days
• Field of Search: 353/20, 353/31, 353/33, 353/34, 353/37, 353/122, 349/5, 349/8, 349/9, 349/18, 349/97, 359/498, 359/502, 359/490, 359/634
• US Class Current: 353/31
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A system for separating light into different spectrums and for recombining the light includes at least one polarizing beamsplitter and at least one retarder stack configured to condition the polarization of input light differently for different spectrums. A device embodying the invention could utilize multiple polarizing beamsplitters and multiple retarder stacks. Alternatively, a system could utilize a single polarizing beamsplitter and a single retarder stack in combination with one or more dichroic beamsplitters. In preferred embodiments, one or more reflective modulator panels are included to separately modulate each separated spectrum of light. Such an embodiment can be used for a color projection system. In each of the embodiments that utilize modulators, distances between the modulators and the focusing optics is essentially the same.

Claims

1. A retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that a first additive primary color spectrum is transmitted from the retarder stack with a first polarization, and a complementary first subtractive primary color spectrum is transmitted from the retarder stack with a second orthogonal polarization.

2. A retarder stack according to claim 1 wherein the first and second polarizations are orthogonal linear polarizations.

3. A retarder stack according to claim 1 further comprising a source of at least partially polarized light.

4. A light combining device comprising:

a beam combiner adapted to receive a first input beam comprising an additive primary color spectrum with a first polarization and a second input beam comprising a complementary subtractive primary color spectrum with a second polarization and combine these first and second input beams into an intermediate beam comprising the first and second input beams; and

a retarder stack adapted to receive the intermediate beam and transmit a beam of white light with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the intermediate beam is transmitted from the retarder stack with the output polarization state, and the complementary subtractive primary color spectrum portion of the intermediate beam is also transmitted from the retarder stack with the output polarization state.

5. A light combining device according to claim 4, further comprising:

a polarizing device adapted to receive the output beam and transmit a desired final polarization state.

6. A light combining device comprising:

a beam combiner adapted to receive a first input beam comprising a first additive primary color spectrum with a first polarization and a second input beam comprising a second additive primary color spectrum with a second polarization and combine these first and second input beams into an intermediate beam comprising the first and second input beams; and

a retarder stack adapted to receive the intermediate beam and transmit an output beam with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the intermediate beam is transmitted from the retarder stack with the output polarization state, and the second additive primary color spectrum portion of the intermediate beam is transmitted from the retarder stack with the output polarization state.

7. A light combining device according to claim 6, further comprising:

a polarizing device adapted to receive the output beam and transmit a desired final polarization state.

8. A light combining device comprising:

a first beam combiner adapted to receive a first input beam comprising a first additive primary color spectrum with a first polarization and a second input beam comprising a second additive primary color spectrum with a second polarization and combine these first and second input beams into a first intermediate beam comprising the first and second input beams;

a first retarder stack adapted to receive the first intermediate beam and transmit a second intermediate beam with an intermediate polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the first intermediate beam is transmitted from the retarder stack with the intermediate polarization state, and the second additive primary color spectrum portion of the first intermediate beam is also transmitted from the retarder stack with the intermediate polarization state;

a second beam combiner adapted to receive the second intermediate beam and a third input beam comprising a third additive primary color spectrum with a third polarization and combine these beams into a third intermediate beam comprising the second intermediate beam and the third input beam;

a second retarder stack adapted to receive the second intermediate beam and transmit an output beam of white light with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first, second and third additive primary color spectrum portions are transmitted from the retarder stack with the output polarization state.

9. A display apparatus comprising:

a first light source adapted to provide a first input beam comprising an additive primary color spectrum with a first polarization;

a second light source adapted to provide a second input beam comprising a complementary subtractive primary color spectrum with a second polarization;

a beam combiner adapted to receive the first input beam and the second input beam and combine these beams into an intermediate beam comprising the first and second input beams; and

a retarder stack adapted to receive the intermediate beam and transmit a beam of white light with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the intermediate beam is transmitted from the retarder stack with the output polarization state, and the complementary subtractive primary color spectrum portion of the intermediate beam is also transmitted from the retarder stack with the output polarization state.

10. A display apparatus according to claim 9 further comprising:

a polarizing device adapted to receive the output beam and output a desired final polarization state.

11. A display apparatus according to claim 9 wherein the first and second light sources are displays that generate image beams.

12. A display apparatus according to claim 9 wherein the beam combiner comprises a polarizing beamsplitter and a dichroic minor.

13. A display apparatus comprising:

a first light source adapted to provide a first input beam comprising an additive primary color spectrum with a first polarization;

a second light source adapted to provide a second input beam comprising an additive primary color spectrum with a second polarization;

a beam combiner adapted to receive the first input beam and the second input beam and combine these beams into an intermediate beam comprising the first and second input beams;

a retarder stack adapted to receive the intermediate beam and transmit an output beam with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the intermediate beam is transmitted from the retarder stack with the output polarization state, and the second additive primary color spectrum portion of the intermediate beam is also transmitted from the retarder stack with the output polarization state.

14. A display apparatus according to claim 13 further comprising a polarizing device adapted to receive the output beam and output a desired final polarization state.

15. A display apparatus according to claim 13 wherein the first and second light sources are displays that generate image beams.

16. A display apparatus according to claim 13 wherein the beam combiner comprises a polarizing beamsplitter and a dichroic mirror.

17. A display apparatus comprising:

a first light source adapted to provide a first input beam comprising a first additive primary color spectrum with a first polarization;

a second light source adapted to provide a second input beam comprising a second additive primary color spectrum with a second polarization;

a third light source adapted to provide a third input beam comprising a third additive primary color spectrum with a third polarization;

a first beam combiner adapted to receive the first input beam and the second input beam and combine these beams into an intermediate beam comprising the first and second input beams;

a first retarder stack adapted to receive the first intermediate beam and transmit a second intermediate beam with an intermediate polarization state, the first retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first additive primary color spectrum portion of the first intermediate beam is transmitted from the retarder stack with the intermediate polarization state, and the second additive primary color spectrum portion of the first intermediate beam is also transmitted from the retarder stack with the intermediate polarization state;

a second beam combiner adapted to receive the second intermediate beam and the third input beam and combine these beams into a third intermediate beam comprising the second intermediate beam and the third input beam;

a second retarder stack adapted to receive the second intermediate beam and transmit an output beam of white light with an output polarization state, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that the first, second and third additive primary color spectrum portions are transmitted from the retarder stack with the output polarization state.

18. A display apparatus according to claim 17 wherein the first, second and third light sources are displays that generate image beams.

19. A display apparatus according to claim 17 wherein the first and second beam combiners comprise a polarizing beamsplitter and a dichroic mirror.

20. A display apparatus comprising:

a first retarder stack adapted to receive a white light beam and transmit a first intermediate beam, the first retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that a first additive primary color spectrum portion of the first intermediate beam is transmitted from the retarder stack with a first polarization and a complementary first subtractive primary color spectrum of the first intermediate beam is transmitted from the retarder stack with a second polarization,

a first beam splitter adapted to divide the first intermediate beam into a first output beam comprising the first additive primary color spectrum portion and a second intermediate beam comprising the complementary first subtractive primary color spectrum of the first intermediate beam;

a second retarder stack adapted to receive the second intermediate beam and transmit a third intermediate beam, the first retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that a second additive primary color spectrum portion of the third intermediate beam is transmitted from the retarder stack with a third polarization and a third additive primary color spectrum of the second intermediate beam is transmitted from the retarder stack with a fourth polarization;

a second beam splitter adapted to divide the third intermediate beam into a second output beam comprising the second additive primary color spectrum portion and a third output beam comprising the third additive primary color spectrum.

21. A display apparatus according to claim 20 further comprising a polarizing device adapted to receive unpolarized white light and output a white light beam with an input polarization.

22. A display apparatus according to claim 20 further comprising a white light source adapted to provide a white light beam.

23. A display apparatus according to claim 20 wherein the white light beam depicts an image to be displayed.

24. A display apparatus according to claim 20 wherein the first and second beam splitters comprise a polarizing beamsplitter and a dichroic mirror.

25. A display apparatus comprising:

a retarder stack adapted to receive a white light beam and transmit an intermediate light beam, the retarder stack comprising at least two retarders, wherein a number, retardance and orientation of the retarders are selected so that a first additive primary color spectrum of the intermediate light beam is transmitted from the retarder stack with a first polarization, and a complementary first subtractive primary color spectrum is transmitted from the retarder stack with a second orthogonal polarization; and

a beam splitter adapted to divide the intermediate beam into a first output beam comprising the first additive primary color spectrum portion and a second output beam comprising the complementary first subtractive primary color spectrum of the intermediate beam.

26. A display apparatus according to claim 25 further comprising a white light source adapted to provide a white light beam.

27. A display apparatus according to claim 26 wherein the white light beam depicts an image to be displayed.

28. A display apparatus according to claim 25 wherein the first and second polarizations are orthogonal linear polarizations.