Abstract: A cholesteric film is formed into an optical device comprising a plurality of layers. The cholesteric film is initially placed in a first predetermined state, for instance heating to a first predetermined temperature, and is then irradiated with narrow band UV radiation. The properties of an upper layer of the film are fixed, for instance for reflecting normally incident infrared radiation of a particular handedness. This process is repeated for different wavelengths of UV fixing radiation so as to penetrate to different depths from the surface of the film in order to form the layers. This method may be used to produce a filter of reduced sensitivity to angle of incidence. In addition to the infrared reflecting layer, red and green reflecting layers are provided. For normally incident radiation, the red and green layers reflect red and green parts R and G, whereas the blue part B of the spectrum is transmitted.

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.

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 cholesteric film is formed into an optical device comprising a plurality of layers. The cholesteric film is initially placed in a first predetermined state, for instance heating to a first predetermined temperature, and is then irradiated with narrow band UV radiation. The properties of an upper layer of the film are fixed, for instance for reflecting normally incident infrared radiation of a particular handedness. This process is repeated for different wavelengths of UV fixing radiation so as to penetrate to different depths from the surface of the film in order to form the layers. This method may be used to produce a filter of reduced sensitivity to angle of incidence. In addition to the infrared reflecting layer, red and green reflecting layers are provided. For normally incident radiation, the red and green layers reflect red and green parts R and G, whereas the blue part B of the spectrum is transmitted.

Abstract: A cholesteric film is formed into an optical device comprising a plurality of layers. The cholesteric film is initially placed in a first predetermined state, for instance heating to a first predetermined temperature, and is then irradiated with narrow band UV radiation. The properties of an upper layer of the film are fixed, for instance for reflecting normally incident infrared radiation of a particular handedness. This process is repeated for different wavelengths of UV fixing radiation so as to penetrate to different depths from the surface of the film in order to form the layers. This method may be used to produce a filter of reduced sensitivity to angle of incidence. In addition to the infrared reflecting layer, red and green reflecting layers are provided. For normally incident radiation, the red and green layers reflect red and green parts R and G, whereas the blue part B of the spectrum is transmitted.

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 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 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 broadband cholesteric polariser includes at least one pair of adjacent layers. The at least one pair includes a cholesteric layer and a compensating layer. The compensating layer has a refractive index perpendicular to the compensating layer greater than a refractive index oriented within the compensating layer.

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 illuminator includes a light guide in the form of a light pipe, one surface of which is provided with a polarization separating layer in the form of an anisotropic layer for separating substantially all of the light of one polarization from the orthogonal polarization component. The anisotropic layer is provided between the light pipe and a reflector. The layer has a first refractive index greater than or equal to that of the light pipe and a second refractive index less than that of the light pipe.