Light guide for liquid detection and cable comprising such a guide.

摘要

A glass-fibre cable has been provided with a signalling conductor for signalling liquid which has penetrated into the cable sheath. The signalling conductor is a glass fibre (6), which is inserted in a protective perforated sheath (2) in the usual way. The inner periphery of this sheath (4) is provided with a wave-shaped pattern (3) on one side, whereas the opposite side is provided with a layer o swelling powder (5) (Figure 1a). As soon as the liquid which has entered the cable, reaches the swelling powder (5 . the volume of this swelling powder will considerably increase, in consequence of which the glass fibre (6) will be pressed against the wave-shaped pattern (3). This causes microbending, which involves a strong, measurable attenuaton of the light signal transmitted through the glass fibre (6) The swelling powder (5) can be applied to a substrate (Figure 1b).