Enclosed corrosion resistant fibre=optic pressure gauge - has isotropic and weakly refringent optical fibre enclosed between ribbons made from corrosion resistant metal

摘要

The pressure gauge consists of an optical fibre (1) which is enclosed and gripped by two metal ribbons (3) (4). The optical fibre is made of isotropic glass and is weakly birefringent. The metal ribbons are made of steel or steel alloys which are resistant to corrosion and other hostile influences. The birefringence of the optical fibre is such that light vibrating parallel to the direction of any pressure applied is displaced in phase from light which is vibrating in an orthogonal direction. This phase displacement is measured and used to determine the external pressure. The space between the optical fibre and the ribbons may be in vacuum in which case the absolute pressure is measured, or the space may be filled with liquid or gas in which case the difference between the external and internal pressures is measured. ADVANTAGE - Gauge is sensitive and is easy to apply to difficult practical environments.