The world's fibre-optics communications market is forecast to reach 8.3 billion dollars annually by 1998. The full exploitation of this enormous potential in science, engineering and other applications requires the precise characterization of optical fibres and their associated systems and components, based on effective and accurate measurements supported by reliable measuring standards and good practice in measurement and calibration. Furthermore, it is necessary to have in place permanent intercomparison practices, both horizontal and vertical. This book provides coverage of trends in this topic of great commercial and scientific interest.