Switchable holographic apparatus
AssigneeSharp Kabushiki Kaisha
InventorPaul May
Life of this patent
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Abstract
A switchable holographic device which includes a first polarizer having a spatially varying direction of polarization. The device also includes a liquid crystal device arranged to act as a controllable phase plate, the liquid crystal device having a predetermined phase shift in one state and substantially no birefringent activity in another state. The liquid crystal device is thus controllable to selectively alter the polarization of at least some of the radiation passing therethrough or to have substantially no optical activity. An output polarizer receives the radiation from the liquid crystal device so that, depending on the state of the liquid crystal device, the hologram is replayed or not replayed.
Claims25
A switchable holographic apparatus, comprising:
- a first polariser having a spatially varying direction of polarisation,
- a switchable retarder switchable between first and second states, and
- a second polariser, wherein
- the switchable retarder is disposed in a radiation path between the first and second polarisers,
- the first polariser comprises a plurality of first pixels having respective directions of polarisation arranged at a first angle to a first direction, and
- the switchable retarder is pixellated and each pixel of the switchable retarder is associated with a plurality of pixels of the first polariser.
A beam steering apparatus comprising a switchable holographic device comprising;
- a first polariser having a spatially varying direction of polarisation,
- a switchable retarder switchable between first and second states, and
- a second polariser, wherein
- the switchable retarder is disposed in a radiation path between the first and second polarisers,
- the first polariser comprises a plurality of first pixels having respective directions of polarisation arranged at a first angle to a first direction, and
- the switchable retarder is pixellated and each pixel of the switchable retarder is associated with a plurality of pixels of the first polariser.
An optical beam steering apparatus, comprising:
- spatially modulated polarising means for providing a spatially modulated source of light comprising a plurality of regions producing plane polarised light polarised along one of a first direction and a second direction,
- an electrically controllable modulator having controllable birefringence for selectively controlling the directions of polarisation of the polarised light, so as to allow a hologram formed in the spatially modulated polarising means to be replayed, and
- a polariser arranged to receive light from the modulator and to transmit components of light polarised along a third direction,
- wherein the electrically controllable modulator is pixellated and each pixel of the electrically controllable modulator is associated with the plurality of regions of the spatially modulated polarising means.
Dependencies are inferred from the claim text.