Abstract: A method of constructing a thin film mirror, which method comprises: (i) attaching a thin film (72) to a suction chamber (68), the suction chamber (68) having edges which are for attaching the thin film (72) and which lie in a desired geometry for the thin film mirror to be constructed; (ii) applying a partial vacuum to the suction chamber (68) such that tension is introduced into the thin film (72); (Hi) adjusting the partial vacuum to form the thin film mirror but with the thin film mirror achieving the desired geometry only over a portion of the thin film mirror; (iv) providing first tensioning means (78, 80) and locally adjusting the first tensioning means (78, 80) such that the portion of the thin film mirror which achieves the desired geometry is increased, the first tensioning means (78, 80) being in contact with the surface of the thin film (72) adjacent to the edge of the suction chamber (68) at a first distance which is substantially uniform from the edge of the suction chamber (68); and providing s

Abstract: Apparatus (2) for constructing a thin film mirror, which apparatus (2) comprises a suction chamber (4), first attachment means (6) positioned at a first side (8) of the suction chamber (4) and for attaching the thin film (10) to the first side (8) of the suction chamber (4), and second attachment means (12) positioned at a second and opposite side (14) of the suction chamber (4) and for attaching the thin film (10) to the second side (14) of the suction chamber (4), the first and second attachment means (6, 12) being such that they secure the thin film (10) against movement when tension is applied in a first direction extending between the first and second attachment means (6, 12), and the first and second attachment means (6, 12) being such that they allow the thin film (10) to move and stretch in a second direction which is at right angles to the first direction and which allows the thin film (10) to be distorted to a desired geometric shape for forming the thin film mirror.

Abstract: Collimated visual display apparatus comprising an aspheric screen (12) and a curved collimating mirror (16), characterised in that the aspheric screen (12) is not a surface of revolution about an axis, the aspheric screen (12) comprises first and second parts (6, 8) which are separated from each other by a third part (10), the first and second parts (6, 8) are curved in cross section and if connected together then they would form a surface of revolution, the third part (10) is straight in cross sectional view and is a short cylindrical centre section, and the collimated visual display apparatus is such that the aspheric screen (12) has an outer curved surface that is viewed via the curved collimating mirror (16) by a user of the collimated visual display apparatus.

Abstract: Apparatus (2) for constructing a thin film mirror, which apparatus (2) comprises a suction chamber (4), first attachment means (6) positioned at a first side (8) of the suction chamber (4) and for attaching the thin film (10) to the first side (8) of the suction chamber (4), and second attachment means (12) positioned at a second and opposite side (14) of the suction chamber (4) and for attaching the thin film (10) to the second side (14) of the suction chamber (4), the first and second attachment means (6, 12) being such that they secure the thin film (10) against movement when tension is applied in a first direction extending between the first and second attachment means (6, 12), and the first and second attachment means (6, 12) being such that they allow the thin film (10) to move and stretch in a second direction which is at right angles to the first direction and which allows the thin film (10) to be distorted to a desired geometric shape for forming the thin mirror.

Abstract: A method of constructing a thin film mirror, which method comprises: (i) providing a suction chamber (2) with edges (4) which lie on a required mirror surface; (ii) providing tensioning means which is forced into contact with film (8) adjacent to at least one of the edges of the suction chamber such that tension in the film parallel to the edge is increased; and (iii) providing holding means (12) for (a) holding the tensioning means (10); (b) locally adjusting holding pressure on the tensioning means (10); and (c) feeding the tensioning means (10) into position after the film (8) has been attached to the suction chamber (2).

Abstract: Display apparatus comprising at least two projectors (1, 2) which are each for providing a display, masks (10, 11), and optical control means (3, 4, 5, 6) for controlling via the masks (10, 11) the brightness of each display across an overlap region formed by parts of the displays that overlap, the optical control means (3, 4, 5, 6) comprising an optical component (13) which spreads light and which is positioned on an illumination side of a liquid crystal display panel (3) in each projector (1, 2).

Abstract: A method of constructing a thin film mirror, which method comprises:

Abstract: An aspheric screen (12) for visual display apparatus, the aspheric screen (12) being such that it is not a surface of revolution about an axis, and the aspheric screen (12) being such that it comprises first and second parts (6, 8) which are separated from each other by a third part (10), the first and second parts (6, 8) being such that they are curved in cross section and if connected together then they would form a surface of revolution, and the third part (10) being such that it is straight in cross sectional view and is a short cylindrical center section.

Abstract: A method of constructing a thin film mirror, which method comprises constructing the mirror from thin plastics film on a suction chamber (8) which has: (i) top and bottom edges (AA', BB') which lie on a required mirror surface; (ii) ends that each have a contact surface to the thin plastics film that lies on a required mirror surface which can be developed from a plane so that the thin plastic film is able readily to be attached; and (iii) no abrupt discontinuities in a mirror support edge part (ABC) of the suction chamber.