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 (Al,Ga)As/(Al,Ga,In)P semiconductor layer structure is etched using an SiCl.sub.4 or an SiCl.sub.4 /(He,Ne) plasma. The etching is carried out at 0.degree. to 80.degree. C. and at a plasma pressure below 1.33.times.10.sup.-1 Pa (1 mTorr). The etched surfaces are sufficiently smooth for the etching process to be used in the production of (Al,Ga)As/(Al,Ga,In)P semiconductor lasers.

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.

Abstract: A three dimensional imaging apparatus may be used as a microscope or camera. The apparatus includes an array of lenses, each of which is aligned with a respective photodetector element. A liquid crystal spatial light modulator has several pixels between each photodetector element and lens. A control circuit controls the modulator so that the pixels in front of each photodetector element act as a moving shutter. The outputs of the photodetector elements are processed and stored to form a three dimensional image.

Abstract: An integrated electro-optical device according to the invention comprises a pixellated liquid crystal modulation layer superimposed over an electronic detection layer. Modulator pads for the liquid crystal layer may be formed as electrically conductive combs to achieve optical polarization. Where the liquid crystal layer provides selective absorption of unpolarized light, and separate polarizers between the liquid crystal and detection layers are therefore unnecessary, the device comprises such a liquid crystal layer superimposed over the electronic detector layer. Further, an integrated electro-optical device, optionally of the above type, has a plurality of pixels of the liquid crystal layer for each pixel of the detector array. This allows optical shuttering of the detector pixels by electrically modulating the pixellated liquid crystal layer.