Abstract: A display apparatus has a switchable birefringent lens array. The display apparatus produces a substantially linearly polarized output. The lens array comprises birefringent material arranged between a planar surface of a first substrate and a relief substrate of a second substrate defining an array of cylindrical lenses. The lens array has electrodes for applying a control voltage across the birefringent material for electrically switching the birefringent material between a first mode and a second mode. In the first mode the lens array modifies the directional distribution of incident light polarized in a predetermined direction. In the second mode the lens array has substantially no effect on incident light polarized in said predetermined direction.

Abstract: In the specification and drawing, a stereoscopic image display apparatus is described and shown with eyewear having a polarization interference filter, wherein the polarization interference filter can distinguish both polarization and spectra.

Abstract: A birefringent lens structure comprises a birefringent lens array capable of directing light of a given polarisation into a directional distribution, the birefringent lens comprising a solid birefringent material and an isotropic material having an interface having a refractive structure. A switchable liquid crystal layer capable of rotating the polarisation of light passing therethrough is arranged adjacent the first birefringent material. The interface between the birefringent material and the liquid crystal layer has an alignment microstructure providing alignment of the birefringent material and the liquid crystal layer. A pair of electrodes for applying an electric field to switch the liquid crystal are arranged with both the lens array and the switchable liquid crystal layer therebetween and a conductive material is incorporated in the lens array to reduce the voltage drop across the lens array.

Abstract: A birefringent lens structure comprises a birefringent lens array capable of directing light of a given polarisation into a directional distribution, the birefringent lens comprising a solid birefringent material and an isotropic material having an interface having a refractive structure. A switchable liquid crystal layer capable of rotating the polarisation of light passing therethrough is arranged adjacent the first birefringent material. The interface between the birefringent material and the liquid crystal layer has an alignment microstructure providing alignment of the birefringent material and the liquid crystal layer. A pair of electrodes for applying an electric field to switch the liquid crystal are arranged with both the lens array and the switchable liquid crystal layer therebetween and a conductive material is incorporated in the lens array to reduce the voltage drop across the lens array.

Abstract: A display apparatus comprises: an emissive spatial light modulator comprising an array of pixels each arranged to output randomly polarized light; a birefringent lens positioned to receive light from the spatial light modulator arranged in a first mode of operation of the display apparatus to direct light of a first polarization component into a first directional distribution and in a second mode of operation of the display apparatus to direct light of a second polarization component into a second directional distribution different from the first directional distribution; a quarter waveplate; and a linear polarizer. The quarter waveplate is arranged between the spatial light modulator and the birefringent lens and the linear polarizer is arranged on the opposite side of the birefringent lens from the quarter waveplate.

Abstract: A display apparatus has a switchable birefringent lens array. The display apparatus produces a substantially linearly polarised output. The lens array comprises birefringent material arranged between a planar surface of a first substrate and a relief substrate of a second substrate defining an array of cylindrical lenses. The lens array has electrodes for applying a control voltage across the birefringent material for electrically switching the birefringent material between a first mode and a second mode. In the first mode the lens array modifies the directional distribution of incident light polarised in a predetermined direction. In the second mode the lens array has substantially no effect on incident light polarised in said predetermined direction.

Abstract: A directional display apparatus, comprising a spatial light modulator comprising an array of pixels and a lens array in which each respective section of the lens array is capable of directing light from a group of pixels aligned with the respective section into nominal viewing windows, is arranged such that each respective section is also capable of directing light from at least one adjacent group of pixels aligned with a section adjacent the respective section into the same nominal viewing windows. This may be achieved by a deflection element, such as a prism element or a hologram, or by each respective section of the lens array having at least one lens surface providing: at least one first region capable of directing light from said group of pixels aligned with the respective section into said nominal viewing windows; and at least one second region capable of directing light from said at least one adjacent group of pixels into the same nominal viewing windows.

Abstract: A display apparatus has a switchable birefringent lens array. The display apparatus produces a substantially linearly polarised output. The lens array comprises birefringent material arranged between a planar surface of a first substrate and a relief substrate of a second substrate defining an array of cylindrical lenses. The lens array has electrodes for applying a control voltage across the birefringent material for electrically switching the birefringent material between a first mode and a second mode. In the first mode the lens array modifies the directional distribution of incident light polarised in a predetermined direction. In the second mode the lens array has substantially no effect on incident light polarised in said predetermined direction.

Abstract: A display apparatus comprises a spatial light modulator and optical elements in series therewith. The optical elements provide a first parallax element being a parallax barrier capable of directing light output from the display apparatus into a first plurality of viewing windows, and a second parallax element capable of directing light output from the display apparatus into a second plurality of viewing windows. In a first mode, the first and second parallax elements have substantially no directional effect on the light output from the display apparatus. In a second mode, the first parallax element directs light output from the display apparatus into the first plurality of viewing windows and the second optical element has substantially no directional effect. In a third mode, the second optical element directs light output from the display apparatus into the second plurality of viewing windows and the first parallax element has substantially no directional effect.

Abstract: A display apparatus comprises a spatial light modulator and optical elements in series therewith. The optical elements provide a first parallax element being a parallax barrier capable of directing light output from the display apparatus into a first plurality of viewing windows, and a second parallax element capable of directing light output from the display apparatus into a second plurality of viewing windows. In a first mode, the first and second parallax elements have substantially no directional effect on the light output from the display apparatus. In a second mode, the first parallax element directs light output from the display apparatus into the first plurality of viewing windows and the second optical element has substantially no directional effect. In a third mode, the second optical element directs light output from the display apparatus into the second plurality of viewing windows and the first parallax element has substantially no directional effect.

Abstract: A directional display apparatus, comprising a spatial light modulator comprising an array of pixels and a lens array in which each respective section of the lens array is capable of directing light from a group of pixels aligned with the respective section into nominal viewing windows, is arranged such that each respective section is also capable of directing light from at least one adjacent group of pixels aligned with a section adjacent the respective section into the same nominal viewing windows. This may be achieved by a deflection element, such as a prism element or a hologram, or by each respective section of the lens array having at least one lens surface providing: at least one first region capable of directing light from said group of pixels aligned with the respective section into said nominal viewing windows; and at least one second region capable of directing light from said at least one adjacent group of pixels into the same nominal viewing windows.

Abstract: A lens array structure comprises two birefringent lens arrays arranged in series, both being capable of operating to direct incident light of one polarisation into a respective directional distribution and to have substantially no effect on incident light of a polarisation perpendicular to said one polarisation. The lens arrays are relatively oriented such that incident light of two perpendicular polarisation components are directed into a directional distribution by a respective one of the birefringent lens arrays and not affected by other one of the birefringent lens arrays. Thus control of the polarisation allows switching between the effects of the two lens arrays. To allow switching into a third mode in which neither of the lens arrays has effect, one of the lens arrays may be active. The lens structure may be employed in a display apparatus to provide a switchable directional display.

Abstract: A light direction switching apparatus and method is described. The light direction switching apparatus comprises a passive birefringent lens (138), e.g. a birefringent lenticular screen, and a switchable polariser (146). By switching the polariser (146), different directional distributions of output light are provided. The light direction switching apparatus may be used with or incorporated in a display device, such as a liquid crystal display device, to provide a display device switchable between a two dimensional mode and an autostereoscopic three dimensional mode, or to provide a multi-user display device where different images are displayed to different viewers. The light direction switching apparatus may also be used to provide switchable brightness enhancement of reflective or transflective display devices. The light direction switching apparatus may also be used to provide a fiber-optic switching apparatus. The switchable polariser may be mechanically switchable or electrically switchable.

Abstract: In one aspect, a display apparatus comprises: an emissive spatial light modulator comprising an array of pixels of organic electroluminescent material each arranged to output substantially polarised light; a switchable polariser being switchable between a first and a second polarisation mode in which the polariser passes light of respective polarisation components; and a birefringent lens positioned to receive light from the spatial light modulator. The birefringent lens is arranged to direct light of a first polarisation component into a first directional distribution and to direct light of a second polarisation component into a second directional distribution different from the first directional distribution, the birefringent lens and the switchable polariser being positioned in series.

Abstract: A semiconductor optical device comprises an active waveguide having a tapered portion, and a passive waveguide extending beyond the end of the active waveguide and optically coupled to the tapered portion of the active waveguide. The passive waveguide beyond the end of the active waveguide supports an optical mode of larger size than the optical mode supported by the active waveguide. The tapered portion of the active waveguide is truncated and the separation between the active waveguide and the passive waveguide is greater than in previously known devices in order to minimize or at least reduce the truncation loss at the truncation.

Abstract: A light direction switching apparatus and method is described. The light direction switching apparatus comprises a passive birefringent lens (138), e.g. a birefringent lenticular screen, and a switchable polariser (146). By switching the polariser (146), different directional distributions of output light are provided. The light direction switching apparatus may be used with or incorporated in a display device, such as a liquid crystal display device, to provide a display device switchable between a two dimensional mode and an autostereoscopic three dimensional mode, or to provide a multi-user display device where different images are displayed to different viewers. The light direction switching apparatus may also be used to provide switchable brightness enhancement of reflective or transflective display devices. The light direction switching apparatus may also be used to provide a fibre-optic switching apparatus. The switchable polariser may be mechanically switchable or electrically switchable.

Abstract: A semiconductor optical device comprises an active waveguide having a tapered portion, and a passive waveguide extending beyond the end of the active waveguide and optically coupled to the tapered portion of the active waveguide. The passive waveguide beyond the end of the active waveguide supports an optical mode of larger size than the optical mode supported by the active waveguide. The tapered portion of the active waveguide is truncated and the separation between the active waveguide and the passive waveguide is greater than in previously known devices in order to minimize or at least reduce the truncation loss at the truncation.

Abstract: The present invention provides a polarization separation element comprising a first array of prisms having a wedge-shaped cross-section, and a second array of prisms also having a wedge-shaped cross section. One of the prism arrays is an array of birefringent prisms. The present invention also provides a polarization conversion system having a polarization separation element of the above type for directing light having a first polarization in a first direction and for directing light having a second polarization different from the first polarization in a second direction different from the first direction; and one or more polarization conversion elements for converting light having the first and second polarizations to light having a substantially common output polarization. The polarization conversion system of the invention is suitable for use in a projection display system.

Abstract: An autostereoscopic 3D display includes a spatial light modulator, for instance of the liquid crystal display type. A backlight and a mask form a plurality of light sources which are imaged by a lenticular screen at first notional viewing windows. A parallax barrier controls the visibility of pixels of the spatial light modulator to form second notional viewing windows. The display forms actual viewing windows whose lateral extent is equal to the product of the lateral extents of the first and second viewing windows and is less than each of these lateral extents.

Abstract: A projection display comprising: a transmissive spatial light modulator (10); an illuminator (1, 20, 21, 30) for illuminating the modulator from the front thereof; and a hologram (32) disposed at the rear of the modulator for imaging and reflecting back through the modulator light from the illuminator received through the modulator.