Coiled elastic sleeving for optical fibre leads - for protection during extension or flexure

摘要

Optical fibres for use in loads for linking other components are enclosed in a hollow sleeve of relatively large diam. and formed into a helix to allow the load to be extended or flexed without producing high local stresses inthe optical fibres. Pref. the sleeve has a composite structure, with a lining of semi-rigid material, specifically polyethylene, and an external sheath of flexible thermoplastic material,specifically PVC or polyurethane. Opt. the sleeve is reinforced by an interlayer of high tensile (RTM-Kevlar) fibres. The sleeve is heat treated to make the helical form elastically recoverable, e.g. by conditioning at 120 deg.C for 20 mins. while close-wound on a mandrel, having a diam. approx. 3 times that of the sleeve. The optical fibre pref. has a coating for protection against rubbing contact with the sleeve walls.