Birefringent interference polarizer

US5612820A · kind A · utility

Assignee

• THE DOW CHEMICAL COMPANY · US

Inventors

• Walter J. Schrenk · Midland, US
• Victor S. Chang · Ellicott City, US
• John A. Wheatley · Stillwater, US

Key dates

• Filing date: May 30, 1995
• Grant date: Mar 18, 1997
• Expiry date: May 30, 2015

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S359/90
• WIPO field: Optics
• WIPO sector: Instruments

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.