Abstract: An illuminable pointer comprising an at least translucent pointer staff and an at least translucent boss suitable for illumination by a light source, wherein the boss includes a staff hole adapted for mounting the pointer for rotation on a spindle and a cavity for holding a known mass to counterbalance the pointer staff, the boss having reflecting surface shaped so to reflect substantially parallel incoming light along the pointer staff towards a focus point outside the distal end of the pointer that the pointer staff is evenly illuminated.

Abstract: The lens includes a plurality of lenslets arranged substantially contiguously in an array. Each lenslet is adapted to receive radiation from a particular zone not substantially overlapping with adjacent zones, and to focus said radiation to a predetermined common point. A detector may be located adjacent said common point and preferably includes at least two detector elements each to detect infra red radiation from a different zone.

Abstract: A fresnel lens in which each of the facets is so dimensioned and configured that the distance between the facet and a focal point of the lens is (n+k) .lambda. where n is an integer, .lambda. is the wavelength of the radiation passing through the lens, and k is a fraction between 0 and 1 which is substantially constant for any facet over the entire face of the lens. Preferably the lens comprises a plurality of zones, each comprising a number of facets, the integer n being constant for each facet of each said zone, but being different for facets of different zones.

Abstract: A light guide for illuminating a keyboard or keypad from behind comprises a transparent grid-like plate having an array of apertures in each of which is accommodated a respective key of the keyboard/keypad. Means are provided for reflecting light from an external source into the plan of the light guide. The individual apertures are surrounded by an upstanding rib formed integrally with the light guide. The top (outer) face of the rib is rendered optically imperfect to promote the escape of light thereform, thus providing an illuminated ring around each key.

Abstract: A light guide for illuminating a keyboard or keypad from behind comprises a transparent grid-like plate having an array of apertures in each of which is accommodated a respective key of the keyboard/keypad. The transparent plate comprises an integral lens aligned with a reflector for directing light from an external source into the plane of the plate. Various plane reflecting surfaces are provided for reflecting the light in a localized path completely surrounding each of the apertures. This arrangement enables the keys to be illuminated with a high degree of uniformity using only relatively few distributed light sources.

Abstract: A lens or lens system for use in reading optical data has as one component a pickup lens having finite or infinite conjugates. The pickup lens is biaspheric where the surfaces may have spherical, paraboloidal or general conic base curves and higher order correction terms up to 40th order when required. Various methods of making such a lens of plastics material are also disclosed.

Abstract: The invention discloses a bi-convex lens having aspheric surfaces, each of substantially identical curvature. The lens may be used in a stand magnifier which comprises a stand adapted to be supported on a surface and to which is attached or attachable such a magnifying lens. At least part of the stand and the lens is tiltable with respect to the surface in either direction from a position where the lens is parallel to the surface, preferably through an angle of up to 20.degree..

Abstract: A convex lens has a geometric axis, defined to be an axis passing through the lens at a central point normally to the general plane of the lens, spaced from its optical axis defined to be an axis passing through the lens between its focal points. The lens may be manufactured from a mould, at least one concave surface of which has a center point spaced from a deepest point, said mould having a feed point at an edge point substantially in a plane extending from said center point through said deepest point to the edge of the concave surface. A transparent plastics material may then be injected into the mould cavity through the feed point.

Abstract: The present invention relates to laminar light guides which are particularly suitable for providing illumination from one or more light sources to a plurality of instruments and other display devices as in a vehicle instrument panel. The guide makes efficient use of the light available from the light sources. The guide comprises a transparent lamina (1,2,3) having at least one integrally formed light input socket (4) for receiving a light source (14). The socket (4) is formed with lens means (13) and reflecting means (15) for directing light from the source into the plane of the lamina where it is internally reflected until encountering extracting means including roughened surfaces (6,7,8,9) for reflecting light diffusely out of the plane of the lamina or conical apertures (5) for reflecting light into a beam transverse to the plane of the lamina.