Apparatus and Method for Dynamically Controlling Light Transmission

Abstract

An apparatus for controlling light transmission from an optical input to an optical output can function as a tunable iris or eclipse, or as a privacy window. The iris / eclipse can use a liquid crystal matrix with a dispersion of dichroic particles that absorb light in one orientation and transmit light in another, such that controlling the liquid crystal with an electric field allows control of the dichroic particles. Alternatively, a layer may be used with a light absorbing liquid or powder material that moves with a charged material in response to a variable electric field applied to the layer. Privacy windows use a plurality of liquid crystal microlenses that can be controlled with an electric field to allow an image of an optical input to be obtainable at an optical output when in a first state, or to render the image irretrievable when in a second state.

Description

FIELD OF THE INVENTION[0001]This invention relates to the field of electrically controllable optical devices, particularly those using liquid crystal.BACKGROUND OF THE INVENTION[0002]Adjustable optical diaphragms and optical shutters are known in the art, and make use of mechanical components that open and close to change the amount of light allowed to pass from an input side to an output side. A tunable iris and shutter has also been shown in which a liquid crystal (LC) cell is used between two polarizers. While the tunable shutter is a rather straightforward solution (where one LC cell with two uniform electrodes is positioned between two cross oriented polarizers), the tunable iris was a similar solution but with one of electrodes being of hole patterned form. In addition, certain electrowetting liquid lenses have been used in the past to form tunable light shutters. However, each of these techniques has drawbacks such as a high loss of light (due to the use of two polarizers), a...

AI Technical Summary

Benefits of technology

"The present invention provides an apparatus for controlling the cross-sectional area through which light passes from an optical input to an optical output. This is achieved by using a liquid crystal orienting matrix layer with dispersed dichroic particles or a control layer containing light absorbing material. An electric field generator creates a spatially uniform electric field or a dynamically variable electric field to reorient the liquid crystal molecules and create the desired shape of the cross-sectional area. The apparatus can be used for controlling the transmission of an image or for providing privacy. The invention also includes the use of carbon nanotubes as the dichroic particles."

Problems solved by technology

This creates a spatially non uniform field strength that causes a reorientation of liquid crystal molecules mainly within a predetermined cross section of the liquid crystal layer.

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