Liquid crystal switching device using the brewster angle

• US 4,755,038 A
• Filed: 09/30/1986
• Issued: 07/05/1988
• Est. Priority Date: 09/30/1986
• Status: Expired due to Term

• Current Assignee: Crystonic Systems Inc.
• Original Assignee: ITT Defense Communications
• Inventors: Baker, Anthony P.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/913,814
• Time in Patent Office: 644 Days
• Field of Search: 350/96.13, 350/96.14, 350/334, 350/337, 350/347 E, 350/347 V, 350/381, 350/395
• US Class Current: 349/196
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/31 Digital deflection, i.e. optical switchingG02F1/33 takes precedence

Abstract

A liquid crystal switching device utilizing the Brewster angle includes a Brewster angle polarizer disposed such that an incident light beam of the device impinges thereon at an angle approximately equal to the Brewster angle.

Claims

1. A liquid crystal switching device;

said device comprises;

means, disposed at the Brewster angle to an incident light beam, for splitting said incident light beam into polarized components; and

means, including a layer of liquid crystal material and disposed in the path of said polarized components, for controllably reorienting the polarization thereof whereby said polarized components can be directed to an output port.

2. Device as claimed in claim 1 further comprises:

means for deflecting said split polarized components such that said polarized components impinge normal to said polarization reorientation means.

3. Device as claimed in claim 2 wherein said deflecting means includes:

a surface, said surface being disposed in the path of said polarized components at an angle thereto at least equal to the critical angle thereof.

4. Device as claimed in claim 1 wherein said polarization reorientation means includes:

first and second boundary surfaces, said layer of liquid crystal material being disposed between said boundary surfaces; and

means for establishing an electromagnetic field in said layer of liquid crystal material.

5. Device as claimed in claim 4 wherein said electromagnetic field establishing means includes;

first and second electrodes, said electrodes being disposed on opposing sides of said layer of liquid crystal material.

6. Device as claimed in claim 1 wherein said light beam splitting means includes:

a first transparent member having a first planar surface;

a second transparent member having a second planar surface; and

a first Brewster angle polarizer, said first Brewster angle polarizer being disposed between said first and second planar surfaces.

7. Device as claimed in claim 6 wherein said light beam splitter means further comprises:

means for deflecting said split polarized components such that said polarized components impinge normal to said polarization reorientation means, said deflecting means including a surface, said surface being disposed in the path of said polarized components at an angle thereto at least equal to the critical angle thereof.

8. Device as claimed in claim 6 wherein said first Brewster angle polarizer comprises:

a plurality of transparent layers having alternating comparatively larger and comparatively smaller indices of refraction.

9. Device as claimed in claim 8 further comprises:

means for recombining said polarized components, said recombiner means being disposed in the path of said polarized components subsequent therealong to said polarization reorientation means.

10. Device as claimed in claim 9 further comprises:

means for deflecting said polarized components subsequent to polarization reorientation means such that said polarized components impinge upon said recombiner means.

11. Device as claimed in claim 10 wherein said recombining means further comprises:

a third transparent member having a third planar surface;

a fourth transparent member having a fourth planar surface; and

a second Brewster angle polarizer, said second Brewster angle polarizer being disposed between said third and fourth planar surfaces.

12. Device as claimed in claim 11 wherein said beam recombining means further comprises:

a second surface, said second surface being disposed in the path of said polarized components at an angle thereto at least equal to the critical angle thereof.

13. Device as claimed in claim 11 wherein said second Brewster angle polarizer comprises:

a plurality of transparent layers having alternating comparatively larger and comparatively smaller indices of refraction.

14. Device as claimed in claim 1 further comprises:

means for recombining said polarized components, said recombining means being disposed in the path of said polarized components subsequent therealong to said polarization reorientation means.

15. Device as claimed in claim 14 further comprises:

means for deflecting said polarized components, said deflecting means being disposed subsequent to said polarization reorientation means such that said polarized components impinge upon said recombiner means.

16. Device as claimed in claim 15 wherein said recombining means further comprises:

a first transparent member having a first planar surface;

a second transparent member having a first planar surface;

a second transparent member having a second planar surface; and

a Brewster angle polarizer, said Brewster angle polarizer being disposed between said first and second planar surfaces.

17. Device as claimed in claim 16 wherein said Brewster angle polarizer comprises:

a plurality of transparent layers having alternating comparatively larger and comparatively smaller indices of refraction.