Birefringent interference polarizer

• US 5,872,653 A
• Filed: 12/18/1996
• Issued: 02/16/1999
• Est. Priority Date: 06/20/1989
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Company
• Inventors: Wheatley, John A., Chang, Victor S., Schrenk, Walter J.
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/768,525
• Time in Patent Office: 790 Days
• Field of Search: 359/488, 359/489, 359/490, 359/494, 359/497, 359/498, 359/500, 359/900, 425/131.1, 425/133.5, 427/163.1, 156/229, 156/244.11, 264/1.31, 264/1.34, 264/1.7
• US Class Current: 359/489.12
• CPC Class Codes: B32B 2307/418 Refractive
• CPC Class Codes: B32B 2307/516 mono-axially
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2369/00 Polycarbonates
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/20 using fillers, pigments, thixotroping agents
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 33/00 Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 1/08 made of polarising materials
• CPC Class Codes: G02B 5/0841 comprising organic materials, e.g. polymers
• CPC Class Codes: G02B 5/0883 with a refractive index gradient rugate filters G02B5/289
• CPC Class Codes: G02B 5/26 Reflecting filters G02B5/28 takes precedence
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: Y10S 359/90 Methods

Abstract

A birefringent interference polarizer which may be fabricated from readily available materials using established coextrusion techniques is provided. The polarizer has a level of light absorption near zero and can be fabricated to polarize and reflect light of specific wavelengths while transmitting light of other wavelengths. The polarizer includes multiple alternating oriented layers of at least first and second polymeric materials having respective nonzero stress optical coefficients which are sufficiently different to produce a refractive index mismatch between the first and second polymeric materials in a first plane which is different from the refractive index mismatch between the first and second polymeric materials in a second plane normal to the first plane. The refractive index mismatch in the first plane is preferably at least 0.03.

Claims

1. A method of making a birefringent interference polarizer comprising the steps of:

providing at least first and second polymeric materials having respective nonzero stress optical coefficients, said first and second polymeric materials comprising copolymers or miscible blends of polymers to adjust the respective refractive indices, stress optical coefficients, and glass transition temperatures of said polymeric materials,

coextruding said first and second polymeric materials in multiple alternating layers, and

stretching said layers such that said first and second polymeric materials become oriented and produce a refractive index mismatch in a first plane which is different from the refractive index mismatch between said first and second polymeric materials in a second plane normal to said first plane.

2. A method of making a tunable birefringent polarizer comprising the steps of:

providing at least first and second elastomeric materials having respective nonzero stress optical coefficients,

coextruding said first and second elastomeric materials in multiple alternating layers, said layers increasing in thickness to produce a layer thickness gradient,

stretching said layers such that said first and second elastomeric materials become oriented and produce a refractive index mismatch between said first and second elastomeric materials in a second plane normal to said first plane to form said tunable birefringent polarizer, and

variably polarizing wavelengths of light with said tunable birefringent polarizer by controlling the degree of elongation of said elastomers.