PROJECTION SYSTEM USING REFLECTIVE POLARIZERS

• US 20100118400A1
• Filed: 01/21/2010
• Published: 05/13/2010
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ma, Jiaying, Gilligan, Gregory E.
• Granted Patent: US 7,967,443 B2
• Time in Patent Office: Days
• US Class Current: 359/495
• CPC Class Codes: G02B 27/1046 for use with transmissive spatial light modulators
• CPC Class Codes: G02B 27/141 using dichroic mirrors
• CPC Class Codes: G02B 27/145 having sequential partially reflecting surfaces
• 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: 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 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A projection system comprising a first imaging component, at least a second imaging component, and a color combiner. The first and second imaging components each comprise an imager and a reflective polarizer that is configured to at least partially separate a light beam from the imager into a first portion and second portion, where the first portion and the second portion have substantially orthogonal polarization states. The first portions of the light beams are directed in the same direction above or below a plane defined by the second portions of the light beams. The color combiner is configured to combine the second portions of the light beams, where the second portions of the light beams have substantially orthogonal polarization states prior to entering the color combiner.

Claims

1. A polarizing beam splitter comprising:

an input prism having an entrance surface and an incident surface; and

a reflective matched z-index polarizer (MZIP) film disposed against the incident surface of the input prism, the reflective MZIP film being oriented to transmit s-polarized light and to reflect p-polarized light with an extinction ratio of at least about 5;

1 with a light beam conditioned at an f number smaller than about 3.0.

2. The polarizing beam splitter of claim 1, wherein the extinction ratio of the polarizing beam splitter is at least about 5:

1 with a light beam conditioned at an f number smaller than about 2.5.

3. The polarizing beam splitter of claim 1, wherein the extinction ratio of the polarizing beam splitter is at least about 30:

1.

4. The polarizing beam splitter of claim 3, wherein the extinction ratio of the polarizing beam splitter is at least about 50:

1.

5. The polarizing beam splitter of claim 1, wherein the entrance surface is configured to transmit the light beam through the input prism toward the incident surface, the light beam having a first angle of incidence relative to the entrance surface, wherein the reflective MZIP film is further oriented at a first orientation angle relative to the entrance surface and is configured to reflect a first portion of the light beam toward the entrance surface, and wherein the first angle of incidence and the first orientation angle are configured to provide a total internal reflection of the first portion of the light beam from the entrance surface.

6. The polarizing beam splitter of claim 1, wherein the first portion of the light beam is a non-image portion of the light beam that is at least partially oriented as p-polarized light, and wherein the light beam further includes an image portion at is at least partially oriented as s-polarized light.

7. The polarizing beam splitter of claim 1, wherein the reflective MZIP film has a z-index mismatch Δ

n_z and an x-index mismatch Δ

n_x, wherein an absolute value of Δ

n_z/Δ

n_x is less than 0.1 over a wavelength band of the incident light.

8. The polarizing beam splitter of claim 7, wherein the absolute value of Δ

n_z/Δ

n_x is less than 0.05 over the wavelength band of the incident light.