Switchable light filter and use thereof

A switchable light filter comprising:

• a first optical element which comprises
• a first layer or a first layer and a plurality of further layers
• wherein each layer comprises a material with a plurality of light-absorbing transition dipole moments,
• wherein, at least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at a maximum, parallel to a first preferential direction selectable for the first optical element or fluctuates around this,
• so that light which is incident in the first optical element is transmitted or at least partially absorbed depending on its incident direction relative to the layers and depending on its polarization state,
• wherein the transition dipole moments in each of the layers can be varied with respect to their orientation and/or their amount between the first state and at least a second state in order to alternatively put the respective layer in at least two different states,
• a polarization filter which is arranged upstream or downstream of the first optical element,
• an electric field generator configured to selectively generate a first electric field or a second electric field, wherein the first state is generated for the first optical elementby applying the first electric field and the second state is generated for the second optical element by applying the second electric field so that
• in a first operating mode in which the first electric field is applied and the transition dipole moments of the layers of the first optical element are oriented along the first preferential direction and which has a first sub-operating mode and a second sub-operating mode, at least 24% of unpolarized light which is incident in the switchable light filter parallel to the first preferential direction is transmitted and at least 85% of unpolarized light which is incident in the switchable light filter at an angle of greater than 30° to the first preferential direction is absorbed wherein the absorption takes place exclusively in a first direction in the first sub-operating mode and exclusively in a second direction perpendicular to the first direction in the second sub-operating mode, and
• in a second operating modein which the second electric field is applied and the transition dipole moments of the layers of the first optical element are oriented parallel to a surface of the polarization filter and perpendicular to a transmission direction of the polarization filter, at least 24% of unpolarized light which is incident in the switchable light filter at any angle to the first preferential direction is transmitted.

A switchable light filter comprising:

• a first optical element and a second optical element, wherein each of the two optical elements comprises:
• a first layer or a first layer and a plurality of further layers
• wherein each layer comprises a material with a plurality of light-absorbing transition dipole moments,
• wherein, at least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at a maximum, parallel to a first preferential direction selectable for the first optical element and to a second preferential direction selectable for the second optical element or fluctuates around these,
• so that light which is incident in the first optical element or second optical element is transmitted or at least partially absorbed depending on its incident direction relative to the layers and depending on its polarization state,
• wherein the first preferential direction and the second preferential direction of the transition dipole moments differ from one another by less than 40°,
• a liquid crystal layerarranged between the first optical element and the second optical element, which liquid crystal layer influences the polarization state of light passing through it depending on a first electric field or second electric field acting on the liquid crystal layer,
• an electric field generator configured to selectively generate the first electric field or second electric field,
• electively, a polarization filter arranged above or below one of the two optical elements, or no polarization filter so that
• either, in a case where a polarization filter present, in a first operating mode in which the first electric field is applied and with a first sub-operating mode, at least 24% of unpolarized light which is incident in the switchable light filter parallel to the first preferential direction or second preferential direction is transmitted and, at least 85% of unpolarized light which is incident in the switchable light filter an angle of greater than 30° to the corresponding preferential direction is absorbed, wherein the absorption takes place exclusively in a first direction in the first sub-operating mode and exclusively in a second direction perpendicular to the first direction in the second sub-operating mode, wherein either the first direction or the second direction is perpendicular to a polarization direction of the polarization filter,
• or, in a case where there is no polarization filter, in a first operating mode in which the first electric field is applied, at least 24% of unpolarized light which is incident in the switchable light filter at any angle is transmitted,
• and regardless of whether or not there is a polarization filter, in a second operating modein which the second electric field is applied, at least 24% of unpolarized light which is incident in the switchable light filter parallel to the first preferential direction or to the second preferential direction is transmitted and at least 85% of unpolarized light which is incident in the switchable light filter at an angle of greater than 30° to the corresponding preferential direction is absorbed.

A switchable light filter comprising

• a first optical element and a second optical element, wherein each of the two optical elements comprises
• a first layer or a first layer and a plurality of further layers
• wherein each layer comprises a material with a plurality of light-absorbing transition dipole moments,
• wherein, at least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at a maximum, parallel to a first preferential direction selectable for the first optical element and to a second preferential direction selectable for the second optical element or fluctuates around these,
• so that light which is incident in the first optical element or second optical element is transmitted or at least partially absorbed depending on its incident direction relative to the layers and depending on its polarization state,
• wherein the transition dipole moments in each of the layers may be varied with respect to their orientation and/or their amount between the first state and at least a second state in order to alternatively put the respective layer in at least two different states,
• an electric field generator configured to selectively generate a first electric field or a second electric field wherein for each of the two optical elements the first state is generated by applying the first electric field and the second state is generated by applying the second electric field
• an optically anisotropic layer for rotating a polarization direction of light passing through the optically anisotropic by 90° arranged between the two optical elements
• electively, a polarization filter arranged above or below one of the two optical elements, or no polarization filter so that:
• in a first operating mode in which the first electric field is applied, at least 24% of unpolarized light which is incident in the switchable light filter at any angle relative to the switchable light filter is transmitted, wherein in the first operating mode, the transition dipole moments of the two optical elements are aligned perpendicular to one another and, in a case where a polarization filteris present, polarization filter transition dipole elements of the polarization filter aligned parallel to the transition dipole moments of the switchable optical element located closest to the polarization filter, and
• in a second operating mode in which the second electric field is applied, at least 24% of unpolarized light which is incident in the switchable light guide parallel to the first preferential direction or second preferential direction is transmitted and, at least 85% of unpolarized light which is incident in the switchable light guide at an angle of greater than 30° to the corresponding preferential direction is absorbed, wherein in the second operating mode, the transition dipole moments of the polarization filter, if present, and the transition dipole moments of the switchable optical element located closest to the polarization filter are oriented perpendicular to one another, and the transition dipole moments of the two optical elements are oriented parallel to one another.

An optical element comprising:

• a first layer, or a first layer and a plurality of further layers
• wherein each layer comprises a material with a plurality of light-absorbing transition dipole moments,
• wherein, at least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at a maximum, parallel to a selectable preferential direction or fluctuates around this, so that
• light which is incident in the optical element is transmitted or at least partially absorbed depending on its incident direction relative to the layers.