Beamsplitting structures and methods in optical systems

• US 7,360,899 B2
• Filed: 05/24/2004
• Issued: 04/22/2008
• Est. Priority Date: 05/22/2003
• Status: Active Grant

• Current Assignee: Synopsys Incorporated
• Original Assignee: Optical Research Associates (Synopsys Incorporated)
• Inventors: Nutter, Douglas A., Cassarly, William J., McGuire, James P. Jr., Rogers, John R.
• Primary Examiner(s): Blackman; Rochelle
• Application Number:
  US10/852,728
• Publication Number:
  US 20070252954A1
• Time in Patent Office: 1,429 Days
• Field of Search: 353/20, 353/30, 353/33, 353/34, 353/37, 353/81, 353/82, 353/47, 353 77- 79, 353/98, 353/99, 359/483, 359487-489, 359494-497, 359/618, 359629-634, 359/636, 359638-640, 359/13, 359/453, 359/456, 359/460, 359/831, 359/833, 359/834, 359/837, 359/880, 349/8, 349/9, 349/57, 349/96, 348/739, 348/744, 348/750, 348/758, 348/759, 348/787, 348/789, 348/836, 345 7- 9
• US Class Current: 353/20
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G03B 21/14 Details
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

Various embodiments involving structures and methods for illumination can be employed, for example, in projectors, head-mounted displays, helmet-mounted displays, back projection TVs, flat panel displays as well as other optical systems. Certain embodiments may include prism elements for illuminating, for example, a spatial light modulator. Light may be coupled to the prism in some cases using fiber optics or lightpipes. The optical system may also include a diffuser having scatter features arranged to scatter light appropriately to produce a desired luminance profile. Other embodiments are possible as well.

Claims

1. An apparatus comprising:

a prism comprising;

a substantially optically transmissive body having first and second input ports for receiving light, an output port for egress of light, and a front face opposite said output port;

a first reflecting polarization beamsplitting surface comprising a wire grid polarizer angled with respect to said first input port to direct polarized light received by said first input port through said output port; and

a second reflecting polarization beamsplitting surface comprising a wire grid polarizer angled with respect to said second input port to direct polarized light received by said second input port through said output port; and

a reflective spatial light modulator,

wherein said prism is disposed with respect to said reflective spatial light modulator such that said polarized light received by said first and second input ports is delivered to said reflective spatial light modulator via said output port and is reflected from said reflective spatial light modulator through said front face of said prism.

2. The prism of claim 1, wherein at least one of said wire grid polarizers is less than about 100 microns thick.

3. The prism of claim 1, wherein said first and second reflecting polarization beamsplitting surfaces converge toward each other to form an apex.

4. The prism of claim 3, wherein said apex is less than about 200 microns wide such that said output port has a dark region resulting from reduced output at the apex of no more than 200 microns wide.