Abstract: In an optical guide, for instance a flexible optical cable, comprising at least two optical fibres and, surrounding the fibres, an outer protective sheath, each of at least some of the optical fibres has a continuous coating of a metallic material, e.g. aluminium or an aluminium-based alloy, which reduces the risk of surface damage of the optical fibre and also serves as an optical screen. At least one covering layer of non-metallic protective material, e.g. resin, enamel or plastics material, may overlie the metallic coating of each metal-coated optical fibre.

Abstract: In an optical transmission system in which light being transmitted from a light-emitting device to a detector device is caused to travel along at least one path built up of at least two optical fibers connected end-to-end, the optical fibre of the interconnected fibres that is nearer the light-emitting device being of smaller cross-sectional area than the other optical fibre, the optical fibres are detachably connected end-to-end by means of a connector comprising two separately formed bodies. One body of the connector has a bore in which one of said two optical fibres is housed and from which a length of said optical fibre protrudes and the other body of the connector has a through-bore which is stepped between its ends and in one part of which the other of said two optical fibres is housed.