The mechanical reliability of stripped and recoated polyimide fibres for optical fibre sensors

A study is made into the effect of stripping the polyimide coating by hot acid immersion on the tensile fracture stress of polyimide-coated optical fibre. It is shown that the strength does not degrade for one or multiple lengths of stripped fibre, nor for long (lengths up to 150 mm) stripped areas. Recoating with polyimide is performed and it is shown that, although strength degradation can occur due to the increased handling, it does not necessarily do so. Strength distributions of pristine, chemically-stripped, laser-ablated and recoated fibres indicate the magnitude of flaws introduced by handling, which are likely to be the cause of strength degradation.