Abstract: A broadband optical retardation device, such as may be used for polarisation encoding of display information or in diffractive optical systems, includes a patterned uniform half wave plate retarder in combination with a non-patterned uniform quarter wave plate retarder having an optic axis oriented at 90° to the xz plane. The patterned retarder consists of alternating first and second regions having first and second optic axes at different orientations to a reference axis, for example at +22.5° and −22.5° to the xz plane. Considering light of wavelength &lgr;° incident on the retarder and linearly polarised in the xy plane, such light is differently polarised by the regions, and the light output by the device includes regions in which the light is right circularly polarised and regions in which the light is left circularly polarised.

Abstract: A diffractive spatial light modulator comprises first and second substrates (1, 2) between which an optical path is defined comprising, in order, first (8a,8b), second (5,6), and third (8a,8b) half wave retarders. The second retarder (6,5) has a fixed optic axis (9c) whereas the first and third retarders have switchable optic axes (9a,9b). The fixed optic axis (9c) is oriented outside the switching ranges of the switchable optic axes (9a,9b). The modulator is pixellated and each pixel comprises a switchable phase-only diffraction grating. Each pixel is switchable between a first mode in which incident light is output in the zeroth order diffraction lobe and a second mode in which incident light is deflected into higher order diffraction lobes. The spatial light modulator may be used in high brightness projection displays.

Abstract: A Liquid crystal device includes: first and second substrates; a layer of liquid crystal disposed between the first and second substrates: and a plurality of picture elements. Each of the picture elements includes: a first electrode disposed on the first substrate; a second electrode electrically insulated from and disposed above the first electrode relative to the substrates; and a third electrode disposed on the second substrate.

Abstract: A display device includes a plurality of strobe electrodes and a plurality of pairs of data electrodes crossed with the strobe electrodes to define a respective pixel at each overlap of one of the strobe electrodes with one of the pairs of data electrodes. The display device further includes a strobe signal source for simultaneously supplying X different strobe signals to each group of X strobe electrodes in turn, where X is an integer greater than one, and a data signal source for supplying any one of a plurality of data signals to the data electrodes such that all combinations of optical states of the X pixels addressed by each group of strobe electrodes and each pair of data electrodes are selectable.

Abstract: A liquid crystal projector comprises a light source (4), a first lenslet array (6) comprising a plurality of first lenslets (10), a second lenslet array (14) comprising a plurality of second lenslets (12) and being con-focal with said first lenslet array (6), and at least one liquid crystal panel (26, 30, 36), wherein said first and second lenslet arrays (6, 14) are non-identical.

Abstract: A diffractive spatial light modulator of the present invention includes a plurality of picture elements, each of the plurality of picture elements, comprises a plurality of first elongate parallel electrodes, a plurality of second elongate parallel electrodes interdigitated with the first electrodes and a third electrode, facing the first and second elongate parallel electrodes; and an address signal generator connected to the first and second elongate parallel electrodes and arranged to supply addressing signals for selectively switching each of the plurality of picture elements, picture element to any one of a non-diffractive state and a plurality of diffractive states of different diffraction efficiencies.

Abstract: A spatial light modulator, for instance of the diffractive liquid crystal type, comprises an addressing circuit and a plurality of pixels. Each of the pixels has a plurality of first elongate electrodes and a plurality of second elongate electrodes interdigitated with the first electrodes. The first electrodes are connected to the addressing circuit whereas the second electrodes are electrically floating.

Abstract: An address generator for a display or spatial light modulator, comprising a first shift register having a plurality of cascade-connected stages for controlling respective first address electrodes of the display or spatial light modulator. The stages of the first shift register include a first reconfigurable shift register stage which is selectively operable in an alternate mode, in which the output of the first reconfigurable shift register stage follows the output of a preceding stage.

Abstract: A dark field projection display includes a light source, a spatial light modulator, and an optical system for directing light from the light source onto the spatial light modulator. The optical system includes a plurality of optical subsystems and a plurality of reflectors. Each of the optical subsystems has an input aperture and is arranged to image light from the light source, the subsystems forming a spatial distribution of source images whose relative positions are different from the relative positions of the input apertures. Each of the optical subsystems further includes a plurality of reflectors disposed at the relative positions of the source images. Each of the reflectors is arranged to reflect light from a respective one of the subsystems onto the spatial light modulator.

Abstract: A diffractive liquid crystal device includes a bistable liquid crystal arranged as pixels with each pixel being addressed by a strobe electrode and a pair of interdigitated data electrodes. A strobe generator supplies an initial blanking pulse to each of the strobe electrodes and then supplies strobe pulses in sequence to the strobe electrodes for at least several frames without any more blanking pulses. A data signal generator supplies data signals to the pairs of data electrodes which switch each pixel to a diffractive or non-diffractive state irrespective of its previous state. In particular, the strobe signals comprise pulses of opposite direction in consecutive frames. To select the non-diffractive pixel state, switching signals are applied to both the first and second electrodes during each frame.

Abstract: A spatial light modulator includes at least three picture elements, each of which includes a plurality of first elongate electrodes which are connected together and a plurality of second elongate electrodes which are connected together and which are interdigitated with the first electrodes. The first electrodes of a second of the picture elements are connected to the second electrodes of a first of the picture elements and the second electrodes of the second picture element are connected to the first electrodes of a third of the picture elements.

Abstract: A diffractive spatial light modulator includes: a layer of electro-optic material; a first electrode arrangement substantially covering a first side of the layer; and a second electrode arrangement substantially covering a second side of the layer. The first electrode arrangement includes a plurality of sets of elongate electrodes, and the elongate electrodes of each of the sets are electrically connected together and interdigitated with the elongate electrodes of at least one of the other acts. The second electrode arrangement includes a plurality of discrete picture element electrodes.

Abstract: A diffractive spatial light modulator includes first and second substrates between which an optical path is defined including, in order, first, second, and third half wave retarders. The second retarder has a fixed optic axis whereas the first and third retarders have switchable optic axes. The modulator is pixellated and each pixel includes a switchable phase-only diffraction grating. Each pixel is switchable between a first mode in which incident light is output in the zero-th order diffraction lobe and a second mode in which incident light is deflected into higher order diffraction lobes. The spatial light modulator may be used in high brightness projection displays.

Abstract: A polarization independent optical phase modulator comprises first and second substrates. A reflector is disposed between the first and second substrates and a quarterwave plate is disposed between the reflector and the first substrate. A polarization dependent electrooptic layer is disposed between the quarterwave plate and the first substrate. The quarterwave plate has an optic axis which is aligned at 45 degrees to the polarization whose phase is modulated by the electrooptic layer.

Abstract: An eye detection system comprises a source, such as an infrared laser diodes for emitting a divergent beam of infrared radiation. A spatial light modulator is controlled so as to act as a deflector for scanning the beam. A detector detects radiation which is retro-reflected by the eye back along the path of the scanning beam. The deflection angle of the SLM and, for a position sensitive detector, the location of the center of illumination on the detector can be used to determine the angle to the center of the pupil of the eye. By subsequently detecting the angle to the glints corresponding to other sources and, the gaze position of the eye on a screen can be determined.

Abstract: A lens is arranged to form a spatially varying intensity distribution at a photoreceptor within a pixel region so as to form a charge pattern thereon. The photoreceptor is associated with a liquid crystal device such that the presence of a suitable recording voltage across the photoreceptor and liquid crystal device causes regions of the liquid crystal device to switch to an opaque state when the light intensity on an associated region of the photoreceptor exceeds a threshold value l.sub.th. Removal of the recording voltage allows the image held in the liquid crystal device to be stored in a non-volatile manner and to be replayed by illumination with a read beam. An analog image having a grey scale can be reproduced from the pixel region. A plurality of pixel regions can be provided as an array so as to record and replay monochrome images.