Patent ID: 11906828
Assignee: SIOPTICA GMBH
Field: Optics (Instruments)
Classification: CPC G | IPC F  G

Claim 8:
9. A switchable light filter switchable between a first operating mode, and a second operating mode, comprising:
a first optical element and a second optical element, wherein each of the first optical element and the second optical element comprises:
a first layer having a material with a plurality of light-absorbing transition dipole moments, and
wherein, 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,
such that the first layer is configured to transmit or at least partially absorb light which is incident in the first optical element or second optical element, depending on its incident direction relative to the layers and depending on its polarization state,

an electric field generator configured to selectively generate a first electric field in the first operating mode and a second electric field in the second operating mode, an optically anisotropic layer arranged between the first optical element and the second optical element, the optically anisotropic layer configured to rotate a polarization direction of light passing through the optically anisotropic layer by 90°, a polarization filter arranged above or below one of the first or the second optical elements, such that the switchable light filter is further configured in the first operating mode to align transition dipole elements of the polarization filter to be parallel with the transition dipole moments of a one of the first or the second optical elements positioned closest to the polarization filter, and
such that the switchable light filter is configured to:
in a first operating mode in which the first electric field is applied, align the transition dipole moments of the two optical elements perpendicular to one another and transmit at least 24% of unpolarized light which is incident in the switchable light filter at any angle relative to the switchable light filter,
and
in a second operating mode in which the second electric field is applied, transmit at least 24% of unpolarized light which is incident in the switchable light guide parallel to the first preferential direction or second preferential direction and absorb 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 and to align the transition dipole moments of the first and second optical elements parallel to one another.