Abstract: A non-compression engine having two or three variable volume mechanisms, an induction-displacer (1) and a combustion-expander (2) or an induction-displacer (1) and a combustion-expander (2) and an atmospheric-cooler (3). A working volume of gas is drawn into the induction-displacer, then displaced into the combustion-expander (2) at substantially constant volume passing through the regenerator (5). The gas in the combustor-expander (2) is further heated by combustion of a fuel then expanded to extract work. The gas is then displaced through the regenerator (5) into the atmospheric-cooler (3) at substantially constant volume, or exhaust from the regenerator at constant pressure. The gas is contracted in the atmospheric-cooler doing atmospheric work. Once the gas has equilibrated with the pressure of the atmosphere it is exhaust from the atmospheric-cooler (3).

Abstract: The invention provides an optical mask (1) for use in blending overlapping tiled images, the optical mask comprising a base (2); an array of elongate sliding elements (10) arranged side by side on the support, each sliding element being independently slidable along an axis and being constrained against lateral translational movement; the mask having a transmission-modifying edge (22) for positioning in a beam of light to modify transmission of the light, the transmission-modifying edge (22) having a profile which is adjustable by moving one or more of the sliding elements (10) along their axes.

Abstract: The invention provides an optical mask (1) for use in blending overlapping tiled images, the optical mask comprising a base (2); an array of elongate sliding elements (10) arranged side by side on the support, each sliding element being independently slidable along an axis and being constrained against lateral translational movement; the mask having a transmission-modifying edge (22) for positioning in a beam of light to modify transmission of the light, the transmission-modifying edge (22) having a profile which is adjustable by moving one or more of the sliding elements (10) along their axes.

Abstract: A non-compression engine having two or three variable volume mechanisms, an induction-displacer (1) and a combustion-expander (2) or an induction-displacer (1) and a combustion-expander (2) and an atmospheric-cooler (3). A working volume of gas is drawn into the induction-displacer, then displaced into the combustion-expander (2) at substantially constant volume passing through the regenerator (5). The gas in the combustor-expander (2) is further heated by combustion of a fuel then expanded to extract work. The gas is then displaced through the regenerator (5) into the atmospheric-cooler (3) at substantially constant volume, or exhaust from the regenerator at constant pressure. The gas is contracted in the atmospheric-cooler doing atmospheric work. Once the gas has equilibrated with the pressure of the atmosphere it is exhaust from the atmospheric-cooler (3).

Abstract: Image display apparatus comprising a projector, at least one primary modulator (4,6,8) for modulating light, an auxiliary modulator (36) for modulating the light modulated by the primary modulator, and an optical device (32) for relaying the light modulated by the primary modulator to the auxiliary modulator (36), the optical device (32) comprising a concave mirror and at least one refractive element.

Abstract: Illumination apparatus (8) which comprises at least two light sources, at least one light collecting device for collecting light from the light sources (10), motion providing means for providing relative motion between the light sources (10) and the light collecting device (14), and control means for controlling the illumination of the light sources (10) such that the light sources (10) are illuminated for a predetermined time period when in a predetermined position relative to the light collecting device (14).

Abstract: An eyepiece (2) for viewing a flat image, which eyepiece (2) has a wide field of view and which eyepiece (2) comprises a cemented doublet of reflecting and refracting optical components, the reflecting and refracting optical components being such that they are each of a different refractive index whereby chromatic aberrations and spherical aberrations are reduced.

Abstract: A support structure (2) for elements forming part of an optical device, which support structure (2) is made of a polymer foam material. The support structure. (2) is lightweight. The optical device may be a head mounted display or a head mounted projector.

Abstract: Illumination apparatus (8) which comprises at least two light sources, at least one light collecting device for collecting light from the light sources (10), motion providing means for providing relative motion between the light sources (10) and the light collecting device (14), and control means for controlling the illumination of the light sources (10) such that the light sources (10) are illuminated for a predetermined time period when in a predetermined position relative to the light collecting device (14).

Abstract: A display device (2) for mobile telecommunications apparatus, which display device comprises: i) a display panel (4); ii) pancake optical means (6) for producing: a) a collimated image to an eye (8) of a viewer so that the image is able to be seen normally from distances as close as it is physically possible to get the eye (8) of the viewer to the display panel (4); and b) an un-collimated image which is equivalent to viewing the display panel (4) directly; iii) polarising filter means (10) for suppressing the un-collimated image; and iv) rotator means (14) for rotating at least part of the filter means (10) through 90° in order to allow the un-collimated image to be used, whereby the display device (2) is such that the user can select an un-collimated viewing mode if the image is of a simple content, and a viewer can select a collimated viewing mode if the image is of a detailed content.

Abstract: Image display apparatus (26) comprising a display panel (28), a screen (30), and image relay apparatus (2), the optical relay apparatus (2) comprising at least one aspherical polymer lens (8, 10, 12,14) and at least one spherical glass lens (4, 6), the said lenses being such that an image is able to be relayed from the display panel to the screen with a predetermined distortion, the optical relay apparatus (2) being such that it has a final aspherical polymer lens (14) which is the said aspherical polymer lens (8, 10, 12, 14) or one of the said aspherical polymer lenses, the final aspherical polymer lens (14) has a first depression (16) on a first side (18) and a second and larger depression (20) on a second side (22), the first side (18) being nearer to the display panel (28) than the second side (22), and the final aspherical polymer lens (14) directs light towards the screen (30) such that the direction of light rays complements the operation of an eyepiece used to view the screen (30).

Abstract: An eyepiece (2) for viewing a flat image, which eyepiece (2) has a wide field of view and which eyepiece (2) comprises a cemented doublet of reflecting and refracting optical components, the reflecting and refracting optical components being such that they are each of a different refractive index whereby chromatic aberrations and spherical aberrations are reduced.

Abstract: Display apparatus (2) for displaying an image by back projection, which display apparatus (2) comprises a projector (4), a screen (6), and a quarterwave retarder (8), the screen (6) being a back projection screen (6) that maintains the polarisation state of incident light (10), the quarterwave retarder (8) being orientated such that its axis at 45° to the axis of polarised light (11) from the projector (4), and the quarterwave retarder (8) being such that it circularly polarizes linearly polarized light that it receives, for example from the projector (4) .