Armoured optical fibre cable for use in an optical communication system for drill hole logging

摘要

An armoured optical fibre cable is formed with a core construction comprising three glass clad optical fibres 51 twisted into a long pitch helix, a sort plastic buffer coat 52 around the fibres 51, and a hard jacket 53 of low diffusivity encasing the buffer coat 52. The sort buffer coat can be formed from silicone rubber and the hard jacket can be formed from a metal tube or a glass filled epoxy polymer. In the latter case, the epoxy polymer jacket is preferably surrounded by a corrosion resistant layer 54 e.g. of a fluorinated hydrocarbon.