Modulation optical system with compensator

• US 6,900,866 B2
• Filed: 11/13/2003
• Issued: 05/31/2005
• Est. Priority Date: 01/07/2002
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Eastman Kodak Company
• Inventors: Kurtz, Andrew F., Silverstein, Barry D., Mi, Xiang-Dong
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US10/712,172
• Publication Number:
  US 20040114079A1
• Time in Patent Office: 565 Days
• Field of Search: 349/5, 349/9, 349/74, 349/96, 349/113, 349/117.1, 349/18, 349/121, 353/8, 353/20, 359/486
• US Class Current: 349/117
• CPC Class Codes: G02B 27/18 for optical projection, e.g. combination of mirror and condenser and objective photographic, cine and overhead projectors G03B21/00; photographic projection printing G03B27/32; photolithographic projectors G03F7/20; projection television H04N5/74; colour projection television H04N9/31
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133548 Wire-grid polarisers
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/133638 Waveplates, i.e. plates with a retardation value of lambda/n
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: H04N 9/3108 by using a single electronic spatial light modulator
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28
• CPC Class Codes: H04N 9/3191 Testing thereof testing of displays in general G09G3/006

Abstract

A modulation optical system (40) provides modulation of an incident light beam. A wire grid polarization beamsplitter (240) receives the beam of light (130) and transmits a beam of light having a first polarization, and reflects a beam of light having a second polarization orthogonal to the first polarization. Sub-wavelength wires (250) on the wire grid polarization beamsplitter face a reflective spatial light modulator. The reflective spatial light modulator receives the polarized beam of light and selectively modulates the polarized beam of light to encode data thereon. The reflective spatial light modulator reflects back both the modulated light and the unmodulated light to the wire grid polarization beamsplitter. The wire grid polarization beamsplitter separates the modulated light from the unmodulated light. A compensator (260) is located between the wire grid polarization beamsplitter and the reflective spatial light modulator (210). The compensator conditions the polarization states of the oblique and skew rays of the modulated beam and includes a spatially variant retardance that corrects for a spatially variant retardance of the reflective spatial light modulator.

Claims

1. A modulation optical system for providing modulation of an incident light beam comprising:

(a) a wire grid polarization beamsplitter for receiving said beam of light, for transmitting light of said beam of light having a first polarization, and for reflecting light of said beam of light having a second polarization orthogonal to said first polarization, wherein sub-wavelength wires on said wire grid polarization beamsplitter face a reflective spatial light modulator;

(b) wherein said reflective spatial light modulator receives said polarized beam of light, having either a first polarization or a second polarization, and selectively modulates said polarized beam of light to encode data thereon, providing both modulated light and unmodulated light which differ in polarization;

(c) wherein said reflective spatial light modulator reflects back both said modulated light and said unmodulated light to said wire grid polarization beamsplitter;

(d) wherein said wire grid polarization beamsplitter separates said modulated light from said unmodulated light;

(e) a compensator is located between said wire grid polarization beamsplitter and said reflective spatial light modulator, wherein said compensator is provided for conditioning the polarization states of the oblique and skew rays of said modulated beam; and

wherein said compensator has a spatially variant retardance that corrects for a spatially variant retardance of said reflective spatial light modulator.

2. A modulation optical system as in claim 1 wherein said spatially variant retardance patterned into said compensator was created with said reflective spatial light modulator operating at a mid-level between the on and off states of said modulator.

3. A modulation optical system as in claim 1 wherein when said reflective spatial light modulator is used in combination with said compensator, a nominally spatially uniform retardance results.

4. A modulation optical system as in claim 1 wherein said spatially variant retardance patterned into said compensator is a spatially variant in-plane retardance.

5. A modulation optical system for providing contrast modulation of an incident light beam comprising:

(a) polarization optics including at least one optical polarizer and one wire grid polarization beamsplitter;

wherein the sub-wavelength wires on said wire grid polarization beamsplitter face a reflective liquid crystal device;

(b) wherein said reflective liquid crystal device is provided for selectively modulating said polarized beam of light having to encode image data thereon in order to form a modulated beam, wherein said reflective liquid crystal device alters a polarization state of said incident beam of light in a controlled manner with said image data and reflects said modulated beam back to said wire grid polarization beamsplitter;

(c) a compensator, located between said wire grid polarization beamsplitter and said reflective liquid crystal device, for conditioning the polarization states of oblique and skew rays of said modulated beam; and

wherein said compensator has a spatially variant retardance that corrects for a spatially variant retardance of said reflective liquid crystal device.

6. A modulation optical system as in claim 5 wherein said spatially variant retardance patterned into said compensator was created with said reflective spatial light modulator operating at a mid-level between the on and off states of said modulator.

7. A modulation optical system as in claim 5 wherein when said reflective spatial light modulator is used in combination with said compensator, a nominally spatially uniform retardance results.

8. A modulation optical system for providing contrast modulation of an incident light beam comprising:

(a) polarization optics including at a polarization beamsplitter;

(b) a reflective liquid crystal device for selectively modulating said polarized beam of light having to encode image data thereon in order to form a modulated beam, wherein said reflective liquid crystal device alters a polarization state of said incident beam of light in a controlled manner with said image data and reflects said modulated beam back to said polarization beamsplitter;

(c) a compensator, located between said polarization beamsplitter and said reflective liquid crystal device, for conditioning the polarization states of oblique and skew rays of said modulated beam; and

wherein said compensator has a spatially variant retardance that corrects for a spatially variant retardance of said reflective spatial light modulator.

9. A modulation optical system as in claim 8 wherein said spatially variant retardance patterned into said compensator was created with said reflective spatial light modulator operating at a mid-level between the on and off states of said modulator.

10. A modulation optical system as in claim 8 wherein when said reflective spatial light modulator is used in combination with said compensator, a nominally spatially uniform retardance results.

11. A modulation optical system as in claim 8 wherein said spatially variant retardance patterned into said compensator is a spatially variant in-plane retardance.