Switchable light filter

Abstract

Switchable light filter (5), comprising: - a first optical element (1) which • a first layer (S1), or a first layer (S1) and several further layers (S2, ...), • wherein each layer (S1, S2, ...) comprises a material with a plurality of light-absorbing transition dipole moments, • wherein each transition dipole moment is aligned parallel to or fluctuates around a first preferred direction selectable for the first optical element (1) with a tolerance of at most 10° in at least a first state, • such that light incident on the first optical element (1) is transmitted or at least partially absorbed depending on its direction of incidence relative to the layers (S1, S2, ...) and its polarization state, - a polarization filter (P) which is arranged upstream or downstream of the first optical element (1) in the direction of incidence,- Means for selectively generating a first electric field (EF1) or a second electric field (EF2), - a liquid crystal layer (3) arranged between the first optical element (1) and the polarizing filter (P), on which the first electric field (EF1) or the second electric field (EF2) acts and which, depending thereon, influences the polarization state of light passing through it, such that - in a first operating mode B1, in which the first electric field (EF1) is present, with a first sub-operating mode B1H and a second sub-operating mode B1V, on the one hand, unpolarized light which occurs parallel to the first preferred direction into the switchable light filter (5) is transmitted to at least 24%, and on the other hand, unpolarized light which occurs at an angle of more than 30° to the first preferred direction into the switchable light filter (5) is absorbed to at least 85%,wherein this absorption in the first sub-operating mode B1H occurs exclusively in a first direction and in the second sub-operating mode B1V exclusively in a second direction perpendicular to the first direction,- in a second operating mode B2, in which the second electric field (EF2) is applied, with the first sub-operating mode B1H and the second sub-operating mode B1V, on the one hand, unpolarized light which is incident parallel to the first preferred direction into the switchable light filter (5) is transmitted to at least 24% and on the other hand, unpolarized light which is incident at an angle of more than 30° to the first preferred direction into the switchable light filter (5) is absorbed to at least 85%, wherein this absorption in the first sub-operating mode B1H occurs exclusively in the second direction and in the second sub-operating mode B1V exclusively in the second direction perpendicular to the first direction,so that the directions of absorption for each of the two sub-operating modes B1H, B1V differ by 90° for the first operating mode B1 and the second operating mode B2.