High efficiency optical tank for two-color liquid crystal light valve image projection with color selective prepolarization

• US 4,544,237 A
• Filed: 12/28/1981
• Issued: 10/01/1985
• Est. Priority Date: 12/28/1981
• Status: Expired due to Fees

• Current Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Gagnon, Ralph J.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Lewis, David
• Application Number:
  US06/334,681
• Time in Patent Office: 1,373 Days
• Field of Search: 350/342, 350/345, 353/31, 353/34, 353/37
• US Class Current: 349/9
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

The invention provides a two-channel liquid crystal light valve image projection system with prepolarization using an oil coupled optical arrangement. A prepolarizing beam splitter is mounted the container in optical alignment with a first surface for splitting and prepolarizing light from a source into first and second beams having first and second polarization states respectively. First and second dichroic separators are mounted within the container for extracting light of a first color from the first beam and light of a second color from the second beam respectively. The separator outputs are recombined by the prepolarizing prism into a single beam which is directed to a second polarizing beam splitter mounted within the container. The second beam splitter splits the single beam and directs light of the first and second polarizations through the second and third apertures, respectively. Liquid crystal light valves mounted at the second and third apertures modulate the polarization state of the exiting light and return it to the second beam splitter to be directed through the output aperture to projection optics for display.

Claims

1. A unitary arrangement comprising:

a first planar polarizing beam splitter for splitting and prepolarizing light from a source into first and second beams having first and second polarization states, respectively;

a first dichroic separator for extracting light of a first color from said first beam;

a second dichroic separator for extracting light of a second color from said second beam;

means for combining the outputs of said first and second dichroic separators into a single beam; and

a second polarizing beam splitter for splitting and polarizing the single beam and directing light of the first color to a first surface and light of the second color to a second surface, wherein the first and second polarizing beamsplitters have transverse axes and each beamsplitter is mounted so that the beamsplitter transverse axes are oriented at a relative 90°

angle.

2. The unitary arrangement of claim 1 including mirror means for directing the outputs of said first and second separators to said means for combining the outputs of said first and second separators.

3. A multi-color image projection system comprising:

first means for providing a source of light energy; and

a unitary tank including a first polarizing beamsplitter for splitting and prepolarizing light energy from said first means into first and second means having first and second polarization states respectively, a first dichroic separator for extracting light energy of a first color from said first beam, a second dichroic separator for extracting light energy of a second color from said second beam, means for combining the outputs of said first and second dichroic separators into a single beam and a second polarizing beamsplitter for directing light energy of the first color to a first light valve, light energy of the second color to a second light valve and light energy from said first and second light valves to a means for projection, wherein the first and second polarizing beamsplitters have transverse axes and each beamsplitter is mounted so that the beamsplitter transverse axes are oriented at a relative 90°

angle.

4. The unitary arrangement of claim 3 wherein the beamsplitters, separators and means for combining are coupled through oil.

5. The multicolor image projection system of claim 3 including first and second cathode ray tubes for providing an input image for said first and second liquid crystal light valves respectively.

6. The multi-color image projection system of claim 3 wherein the beamsplitters, separators and means for combining are coupled through oil.

7. The multi-color image projection system of claim 3 including mirror means for directing the outputs of said first and second separators to said means for combining the outputs of said first and second separators.

8. In an optical system including means for providing light energy, first and second liquid crystal light valves, first and second cathode ray tubes for use with said first and second liquid crystal light valves, respectively, and a means for projection, an improved optical arrangement comprising:

a container having a plurality of surfaces joined together to form a chamber suitable for holding fluid, including a first surface for providing an input aperture, second and third surfaces each providing an output aperture for polarized and an input aperture for modulated light, energy and a fourth surface for providing an output aperture;

a prepolarizing beamsplitter mounted within said chamber for splitting and prepolarizing light energy from the source into first and second beams having first and second polarization states respectively;

a first dichroic separator mounted within said chamber for extracting light energy of a first color from said first beam and a second dichroic separator for extracting light energy of a second color from said second beam;

means mounted in said chamber for combining the output of the first and second separators to form a single beam; and

a main polarizing beamsplitter mounted in said chamber for directing light of a first color and polarization through the second aperture to the first liquid crystal light valve and light energy of a second color and polarization through the third aperture to the second liquid crystal light valve and directing intensity modulated light energy through said fourth aperture to a means for projection, wherein said prepolarizing beamsplitter and said main polarizer have transverse axes and each beamsplitter is mounted so that the beamsplitter transverse axes are oriented at a relative 90°

angle.

9. The optical system of claim 8 wherein the prepolarizing beamsplitter and the main polarizing beamsplitter are substantially identical.

10. A unitary arrangement comprising:

a first polarizing beamsplitter for substantially splitting and polarizing light from a source into first and second beams having S and P polarization states, respectively;

a first dichroic separator for substantially extracting red light from said first beam;

a second dichroic separator for substantially extracting green light from said second beam;

means for combining the outputs of said first and second dichroic separators into a single beam; and

a second polarizing beamsplitter for polarizing the single beam and directing red light to a first surface and green light to a second surface, wherein the first and second polarizing beamsplitters have transverse axes and each beamsplitter is mounted so that the beamsplitter transverse axes are oriented at a relative 90°

angle.

11. The unitary arrangement of claim 10 wherein the beamsplitters, separators and means for combining are coupled through oil.

12. The unitary arrangement of claim 10 including mirror means for directing the outputs of said first and second separators to said means for combining the outputs of said first and second separators.

13. The unitary arrangement of claim 10 wherein the first and second polarizing beamsplitters are substantially identical.