Liquid crystal devices using a linear electro-optic effect

US5847790A · kind A · utility

Assignee

• S.T. Lagerwall S.A.R.L. · FR

Inventors

• Gunnar Andersson
• Ingolf Dahl · Mölndal, SE
• Lachezar Komitov · Handen, SE
• Sven T. Lagerwall · Göteborg, SE
• Kent Skarp · Nordstraße, SE
• Bengt Stebler · Göteborg, SE

Key dates

• Filing date: Jun 7, 1995
• Grant date: Dec 8, 1998
• Expiry date: Jun 7, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F2203/02
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A device for influencing light has a polarizer, a ferroelectric or electroclinic response type liquid crystal halfwave plate whose liquid crystals are in the smectic phase with bookshelf geometry and have molecular axes which are rotatable around a first direction corresponding to the direction of incoming light in response to an electric field applied across the electrodes on either side of the halfwave plate, a quarter wave retarder plate, and a mirror. The polarizer, plates and mirror are arranged such that incoming light is passed from the polarizer through the liquid crystal plate and the retarder plate, and is reflected by the mirror in a second direction opposite to the first direction back through the retarder and the liquid crystal plate so as to provide a reflected polarized light plane to the polarizer. The polarizer has a first polarization direction set parallel to one electrically selectable molecular axis direction of the liquid crystal molecules, which is selected in response to a first electric field level. The retarder plate has its slow axis inclined either 45.degree. or 135.degree. relative to the optic axis of the liquid crystal. The liquid crystal, furthermore…