Abstract: An optical device which is suitable for use in a projection display comprises a spatial light modulator, such as a liquid crystal device, with a microlens array disposed on its front surface. The microlenses are of convergent type, such as lenticules. The spatial light modulator is of the reflective type and comprises a plurality of rear reflectors, each of which has convergent optical power in at least one direction. The reflectors are arranged such that, for a given direction of illumination, each reflector forms an image of the aperture A of a microlens on the aperture B of another microlens or at a different position on the same microlens. When used in, for example, a projection display, light losses caused by vignetting are reduced.

Abstract: A 3D camera includes at least two detector heads which are moveable laterally with respect to each other but whose optical are maintained parallel. Each of the detector heads includes a zoom lens and a detector. A user selects the separation between the detector heads and the camera electronics automatically select the field of view by controlling the zoom lenses as a function of the detector head separation.

Abstract: A reflective liquid crystal display device (LCD) (40) includes: a substrate (60), a reflecting layer (61), a liquid crystal layer (62), an electrode layer (63), a color filter layer (64), an upper substrate (65), and a polarizer (66). The reflective liquid crystal display device further includes a holographic field lens (67). By providing the holographic field lens, the LCD can be used with a closely placed, offset light source (41), since the holographic field lens simultaneously concentrates light incident on the LCD and redirects it in a preferred direction. The holographic field lens can be provided within the structure of the LCD.

Abstract: A directional display comprises a display arrangement such as a spatial light modulator and a rear parallax barrier illuminated by a suitable backlight. The spatial light modulator and the parallax barrier cooperate to produce Fresnel diffraction which results in spatially non-uniform brightness across viewing windows of the display. Also, where the spatial light modulator has pixels of non-constant vertical aperture, further variations in the intensity profile at the windows occurs. In order to compensate for this, a mask is provided, for instance between the parallax barrier and the backlight. The mask cooperates with the parallax barrier to produce an intensity pattern having variations which are the inverse of the variations in intensity pattern produced by the parallax barrier and the spatial light modulator. The variations are superimposed and substantially cancel each other out so as to result in viewing windows which have substantially uniform light intensities.

Abstract: A parallax barrier comprises a plurality of parallel vertical apertures or apertures. In a direction transverse to the apertures, the apertures have an optical transmission function which comprises a plurality of sub-apertures so that the function varies in this direction. In general, the function is constant in a direction parallel to the apertures or apertures. Such a barrier may be used with a spatial light modulator such as a liquid crystal display to form an autostereoscopic 3D display.

Abstract: A directional display comprises a display arrangement such as a spatial light modulator and a rear parallax barrier illuminated by a suitable backlight. The spatial light modulator and the parallax barrier cooperate to produce Fresnel diffraction which results in spatially non-uniform brightness across viewing windows of the display. Also, where the spatial light modulator has pixels of non-constant vertical aperture, further variations in the intensity profile at the windows occurs. In order to compensate for this, a mask is provided, for instance between the parallax barrier and the backlight. The mask cooperates with the parallax barrier to produce an intensity pattern having variations which are the inverse of the variations in intensity pattern produced by the parallax barrier and the spatial light modulator. The variations are superimposed and substantially cancel each other out so as to result in viewing windows which have substantially uniform light intensities.

Abstract: A three dimensional display is provided which can. operate in an autostereoscopic mode, requiring no viewing aid, and a stereoscopic mode, requiring a viewing aid such as polarized spectacles. In the autostereosocopic mode, light from illuminators is imaged by lenses through LCD display panels at regions where the left and right eyes of an observer are located. Thus, a two dimensional image displayed on one panel is visible to the right eye of the observer whereas a two dimensional image displayed by the other panel to visible to the left eye of the observer. In the stereoscopic mode, light from the illuminators through the LCD panels is visible throughout an extended region by both eyes of the observer. However, the light from the panels is polarized in mutually perpendicular directions and the spectacles comprise polarizers for the left and right eyes which substantially pass only light corresponding to the left and right images, respectively.

Abstract: A parallax barrier includes a polarization modifying layer having aperture regions, for supplying light of a second polarization when receiving light of a first polarization, separated by barrier regions, for supplying light of a third polarization different from the second polarization when receiving light of the first polarization, and a polarizer selectively operable in a first mode and a second mode. At least one of the aperture regions and the barrier regions alters the polarization of light passing therethrough. The polarizer passes light of the second polarization and blocks light of the third polarization in the first mode and passes light of the third polarization in the second mode.

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.

Abstract: An observer tracking directional display comprises a spatial light modulator associated with a movable parallax optic. An observer tracker determines the position of an observer and controls the position of the optic by way of an electromechanical transducer and a mechanical transmission. The mechanical tracking arrangement has a plurality of stationary positions for the parallax optic relative to the spatial light modulator (SLM) and steps between these positions so as to optimize the viewing windows for the current position of the observer.

Abstract: A parallax barrier includes a polarisation modifying layer having aperture regions, for supplying light of a second polarisation when receiving light of a first polarisation, separated by barrier regions, for supplying light of a third polarisation different from the second polarisation when receiving light of the first polarisation, and a polariser selectively operable in a first mode and a second mode. At least one of the aperture regions and the barrier regions alters the polarisation of light passing therethrough. The polariser passes light of the second polarisation and blocks light of the third polarisation in the first mode and passes light of the third polarisation in the second mode.

Abstract: A directional display comprises a display arrangement such as a spatial light modulator and a rear parallax barrier illuminated by a suitable backlight. The spatial light modulator and the parallax barrier cooperate to produce Fresnel diffraction which results in spatially non-uniform brightness across viewing windows of the display. Also, where the spatial light modulator has pixels of non-constant vertical aperture, further variations in the intensity profile at the windows occurs. In order to compensate for this, a mask is provided, for instance between the parallax barrier and the backlight. The mask cooperates with the parallax barrier to produce an intensity pattern having variations which are the inverse of the variations in intensity pattern produced by the parallax barrier and the spatial light modulator. The variations are superimposed and substantially cancel each other out so as to result in viewing windows which have substantially uniform light intensities.

Abstract: A directional display comprises a display arrangement such as a spatial light modulator and a rear parallax barrier illuminated by a suitable backlight. The spatial light modulator and the parallax barrier cooperate to produce Fresnel diffraction which results in spatially non-uniform brightness across viewing windows of the display. Also, where the spatial light modulator has pixels of non-constant vertical aperture, further variations in the intensity profile at the windows occurs. In order to compensate for this, a mask is provided, for instance between the parallax barrier and the backlight. The mask cooperates with the parallax barrier to produce an intensity pattern having variations which are the inverse of the variations in intensity pattern produced by the parallax barrier and the spatial light modulator. The variations are superimposed and substantially cancel each other out so as to result in viewing windows which have substantially uniform light intensities.

Abstract: An optical device includes a plurality of picture elements the phase and/or amplitude transmission of which vary in the lateral direction of the optical device reducing the level of diffraction caused by the device.

Abstract: An image tracking system which is configured to present a sequence of images, determine the position of a target image in a previously presented image, determine movement of the target image between the previously presented image and a subsequently presented image, and indicate the position of the target image in the subsequently presented image as the aforementioned determined position modified by the determined movement.

Abstract: A light source comprises an array of contiguous transparent blocks, each of which contains a light emitter such as a cold cathode fluorescent tube. The blocks have a transparent front surface which may be optically diffusing, the other surfaces being coated with a thin optically reflective layer so that each block acts as a light guide. The tubes are independently controllable, for instance so as to simulate a moving light source which may be controlled so as to track the position of an observer of a 3D display.

Abstract: An autostereoscopic display comprises an SLM which is controlled to provide an image display and a signal display. A parallax optic has a first portion which cooperates with the image display to form a plurality of viewing windows. A second portion of the parallax optic forms first and second images visible to an observer at alternate viewing windows so as to allow the observer to distinguish between desired orthoscopic viewing zones and undesirable viewing positions such as pseudoscopic positions.

Abstract: A passive polarisation modulating optical element comprises a layer of birefringent material. The layer has substantially fixed birefringence and comprises retarder regions forming a regular pattern, for instance to act as a parallax barrier for a 3D display. The retarders have optic axes aligned in different directions from each other. The element may be associated with a polariser, for instance an output polariser of a liquid crystal device, with the polarising direction of the polariser being parallel to the optic axis of the retarders. Thus, the retarders have no effect on the intensity of light passing through the element whereas the retarders act as half waveplates and rotate the polarisation vector of light passing therethrough, for instance by 90.degree..

Abstract: A parallax barrier includes a polarisation modifying layer having aperture regions, for supplying light of a second polarisation when receiving light of a first polarisation, separated by barrier regions, for supplying light of a third polarisation different from the second polarisation when receiving light of the first polarisation, and a polariser selectively operable in a first mode and a second mode. At least one of the aperture regions and the barrier regions alters the polarisation of light passing therethrough. The polariser passes light of the second polarisation and blocks light of the third polarisation in the first mode and passes light of the third polarisation in the second mode.

Abstract: A liquid crystal spatial light modulator comprises columns and rows of picture elements. The columns are arranged as groups of columns, for instance under respective parallax generating elements in an autostereoscopic 3D display. The picture elements are arranged as sets to form color picture elements such that the picture elements of each set are disposed at the apices of a polygon, such as a triangle, and are disposed in corresponding columns of the groups of columns.