Distributed optical-fibre sensors for the measurement of pressure, strain and temperature

An analysis of fully-distributed optical-fibre sensor (DOFS) systems, with particular reference to the measurement of pressure, strain and temperature in industrial environments, is presented. The analysis seeks to establish relationships between primary system parameters such as sensitivity, accuracy, bandwidth, resolution and dynamic range. These relationships allow appropriate trade-offs to be made in order to meet any given set of industrial requirements, and also allow quantitative comparisons to be made amongst the various kinds of DOFS systems. The physical phenomena which may be used in DOFS are considered, leading to the conclusion that, to give a performance likely to be generally attractive for industrial application, systems which use optical phase modulation by the measurand should be used. The present state-of-the-art with regard to component technology in support of DOFS is reviewed, with the conclusion that most of the requirements can be met already, and that present trends should soon take care of the remainder.