Rapid starting, high-speed liquid crystal variable optical retarder

A rapid starting, high-speed liquid crystal variable optical retarder comprising:

• a liquid crystal cell which includes a pair of generally parallel electrode structures that contain a mixture of a chiral agent and a nematic liquid crystal material which has directors, the inner surface of each electrode structure including a director alignment layer which has been conditioned so that the directors of the liquid crystal material in contact therewith become substantially uniformly aligned to form tilt bias angles with the conditioned surface, the tilt bias angles of the directors in contact with the conditioned surface of one electrode structure being defined in a rotational sense opposite to the tilt bias angles of the directors in contact with the other conditioned surface of the other electrode structure and the projections of the directors in contact with the conditioned surfaces being aligned so that the projections onto one of the conditioned surfaces are parallel to the projections onto the other conditioned surface;
• and
• the liquid crystal cell being operable in response to an applied electric field to cause a substantial number of the surface noncontacting directors to align in substantially end-to-end relation in a direction generally normal to the conditioned surfaces to provide a first amount of optical retardation through the cell of light incident to one of the surfaces of the electrode structures, in rapid response to a substantial diminution of the magnitude of the electric field to cause at least some of the surface noncontacting directors within the interior of the cell to rotate about axes that are perpendicular to the normal to the conditioned surfaces to provide a second amount of optical retardation of light incident to one of the surfaces of the electrode structures, and in response to a relatively prolonged absence of the electric field to inhibit director relaxation to a splayed state.