Abstract: The invention relates to a color filter layer of a cholesterically ordered material, in which the axis of the molecular helix is directed perpendicularly to said layer. According to the invention, the color filter layer comprises at least one dye which is able to absorb undesired colors caused by color shifts. A correct choice of the bandwidth of the primary colors of the color filter layer and the dyes significantly alleviates the problem of undesired color shift. The invention also relates to a liquid crystal color display device of the reflective type, which is provided with such a color filter layer.

Abstract: An illumination system (3) comprises an optical waveguide (9) of an optically transparent material having an exit surface (19) and four end faces (13, 14, 15, 16). The light from a light source (11) is coupled into the optical waveguide (9) via at least one of the end faces (13). The illumination system, for an LCD, further has a reflective polarizer (21) in combination with a diffuser (23) for polarizing the light supplied by the light source (11). The reflective polarizer (21) is integrated with the optical waveguide and constitutes the surface (25) of the optical waveguide (9) which is located opposite the exit surface (19). The diffuser (23) is present on a surface of the polarizer (21) remote from the optical waveguide (9).

Abstract: The Application relates to an illumination system comprising a fluorescent lamp and a broadband, cholesteric polarizer. Such a polarizer contains a layer of a polymeric material having a cholesteric order, which material is ordered in such a way that the axis of the molecular helix extends at right angles to the layer. The broadband character of the polarizer is obtained by causing the pitch of the molecular helix to increase from a minimum value at a first surface of the cholesteric layer to a maximum value at the second surface of the layer. In accordance with the invention, the polarizer should be positioned in the illumination system in such a manner that the cholesteric layer is directed towards the fluorescent lamp with its first surface. In addition, the value of the product p.sub.max.n.sub.e of the maximum value of the pitch in the cholesteric layer p.sub.max and of the extraordinary refractive index n.sub.e must range between 0.61 micron and 0.76 micron.

Abstract: A molecularly oriented synthetic resin composition whose coefficient of linear thermal expansion in two mutually perpendicular directions, below the glass-transition temperature, is at least a factor of 3 smaller than in a third direction extending perpendicularly to the first two directions, is manufactured by curing a liquid-crystalline composition having a helicoidal order of molecules, so as to form a polymer network. The resins thus obtained are suitable for use as claddings on materials having a coefficient of thermal expansion which is smaller than that of most synthetic resins.

Abstract: The invention provides an optical glass fibre having a synthetic resin coating and a method of manufacturing same, the first layer of the synthetic resin coating being formed from a curable polyether urethane acrylate composition.The glass transition temperature of the synthetic rubber formed after curing is reduced to -50.degree. C. or lower by increasing the molecular weight of the polyether urethane acrylate and, if necessary, by using aromatic instead of aliphatic urethanes. During coating the viscosity is low due to the presence of monofunctional acrylates of low viscosity. The curable synthetic composition exhibits a high curing rate.

Abstract: The invention provides an optical glass fiber having a synthetic resin cladding, in which the first layer of the synthetic resin cladding is formed from a curable synthetic resin composition which comprises a polyurethane acrylate and a siloxane copolymer containing acrylate groups.The synthetic rubber obtained by curing has the suitable properties of polysiloxane claddings, and additionally a greater mechanical strength as well as a greater resistance to wear.

Abstract: The invention provides an optical fibre having a synthetic resin cladding, comprising a glass fibre, a first cladding layer of a synthetic rubber and a subsequent cladding layer of a synthetic resin the molecules of which are oriented substantially in the longitudinal direction of the glass fibre, in which a low application temperature, a low pressure and a high cladding rate can be used in that the oriented synthetic resin is formed from a curable synthetic resin composition which comprises one or more oligomeric compounds the molecules of which comprise reactive groups and the molecular weight of which is smaller than 5000.The invention further relates to a method of manufacturing such an optical fibre and a device for cladding a glass fibre with a curable synthetic resin composition in which an elongation flow in the curable synthetic resin composition is produced to effect the orientation in the curable synthetic resin composition.

Abstract: The invention provides an optical glass fibre having a synthetic resin cladding and a method of manufacturing same, in which the first layer of the synthetic resin cladding is formed from a curable polysiloxane composition.The curing rate is increased by the presence of acrylate groups. The refractive index (exceeding 1.46) and the glass transition temperature (lower than -50.degree. C.) can be adjusted by the ratio of the dimethyl siloxane groups, methyl phenyl siloxane groups and diphenyl siloxane groups present. The curing rate can furthermore be increased by the addition of monomeric acrylate compounds.