Electrically controllable optical element, in particular thin-film cell having an optically active surface profile, and method for the production thereof

An electrically controllable optical element in a form of a thin-film cell, said thin-film cell comprising:

• a first substrate having an inner surface on which a first conductive layer is applied;
• a second substrate having an inner surface in which a second conductive layer is applied;
• and
• a starting Kerr mixture filled between the first conductive layer and the second conductive layer;
• wherein the starting Kerr mixture comprises a mixture of dipolar, rod-shaped molecules and semi-mesogens as active components,
• wherein the starting Kerr mixture is a thin layer with a photopolymerization-produced, wide-mesh, anisotropic network formed between the first conductive layer and the second conductive layer of the thin-film cell,
• wherein the active components, without an electric field in a working temperature range, are isotropic,
• wherein by electrically continuous adjustment of voltage or by applying a constant voltage, a change in a voltage induced phase shift or in a refractive index deviation is generated in the optical element, and
• wherein an optically effective surface profile is incorporated on one or both of the inner surface of the first substrate and the inner surface of the second substrate.

A method for producing an electrically controllable optical element in a form of a thin-film cell having a first substrate having an inner surface on which a first conductive layer is applied, a second substrate having an inner surface in which a second conductive layer is applied and a starting Kerr mixture filled between the first conductive layer and the second conductive layer, the method comprising:

• a) providing a mixture comprising dipolar, rod-shaped molecules and semi-mesogens as active components, reactive mesogens, photoinitiators and aliphatic monomers as the starting Kerr mixture,
• b) filling the starting Kerr mixture into a thin-layer between the first conductive layer and the second conductive layer,
• c) cooling the starting Kerr mixture to a lower temperature than room temperature to form a liquid crystal phase with a homeotropic orientation,
• d) irradiating the liquid crystal phase with the homeotropic orientation with UV radiation to generate radicals that cause a polymerization of the oriented reactive mesogens such that a wide-meshed, loose anisotropic network of reactive mesogens crosslinked with aliphatic monomers in the starting mixture results, and
• e) incorporating an optically active surface profile on one or both of the inner surface of the first substrate and the inner surface of the second substrate such that without a voltage in a working temperature range, a composite of the active components is isotropic and upon application of the voltage, molecules of the composite are oriented in direction of E field lines.