An Introduction to Distributed Optical Fibre Sensors (Series in Fiber Optic Sensors)

This book explains physical principles, unique benefits, broad categories, implementation aspects, and performance criteria of distributed optical fiber sensors (DOFS). For each kind of sensor, the book highlights industrial applications, which range from oil and gas production to power line monitoring, plant and process engineering, environmental monitoring, industrial fire and leakage detection, and so on. The text also includes a discussion of such key areas as backscattering, launched power limitations, and receiver sensitivity, as well as a concise historical account of the field’s development. Content: Cover Half title Series in Fiber Optic Sensors Title Copyright Dedication Contents Series Preface Foreword Preface Author List of Symbols List of Abbreviations Part ONE Fundamentals Chapter 1 Introduction 1.1 The Concept of Distributed Optical Fibre Sensors 1.1.1 Optical Fibre Sensors 1.1.2 The Advent of Multiplexed Sensors 1.1.3 Distributed Optical Fibre Sensors 1.2 Historical Development of DOFS 1.2.1 Optical TDR: An Enabling Technology 1.2.2 Distributed Temperature Sensors 1.2.3 Elastic and Inelastic Scattering 1.2.4 Raman OTDR 1.2.5 Brillouin-Based Distributed Sensing1.2.6 Distributed Sensing with Rayleigh Backscatter 1.3 Performance Criteria in Distributed Fibre-Optic Sensors 1.3.1 Four Key Criteria 1.3.1.1 Measurand resolution 1.3.1.2 Range 1.3.1.3 Spatial resolution 1.3.1.4 Sampling resolution 1.3.1.5 Measurement time 1.3.2 Interplay between Performance Criteria 1.3.3 Estimation of Key Performance Parameters 1.3.4 Sensor Accuracy and Cross-Talk 1.4 History of Commercialisation: Successes and Failures 1.4.1 Raman DTS 1.4.2 Commercial Brillouin-Based Distributed Strain and Temperature Sensors 1.4.3 Distributed Vibration Sensing1.5 Other Technologies 1.6 Distributed Sensing and Dense Point Sensor Arrays 1.7 Organisation of the Book References Chapter 2 Optical Fibre Technology 2.1 Propagation in Optical Fibres 2.1.1 Types of Optical Fibre 2.1.1.1 Step-index multimode fibres 2.1.1.2 Graded-index multimode fibres 2.1.1.3 Single-mode optical fibres 2.1.2 Loss Mechanisms 2.1.2.1 Absorption 2.1.2.2 Scattering 2.1.2.3 Other loss mechanisms 2.1.3 Bandwidth of Optical Fibres 2.2 Construction of Optical Fibres 2.3 Principal Components Used in Distributed Sensing Systems 2.3.1 Lasers2.3.1.1 Broad contact semiconductor lasers 2.3.1.2 Fabry-Pérot single-mode laser diodes 2.3.1.3 Semiconductor distributed feedback lasers 2.3.1.4 External cavity feedback semiconductor lasers 2.3.1.5 Semiconductor DFB lasers with active phase/frequency feedback 2.3.1.6 Fibre DFB lasers 2.3.1.7 Tunable lasers 2.3.1.8 Symbols for optical sources 2.3.2 Optical Amplifiers 2.3.2.1 Doped fibre amplifiers 2.3.2.2 Semiconductor optical amplifiers 2.3.2.3 Symbol for optical amplifiers 2.3.3 Fused-Taper Couplers 2.3.4 Micro-Bulk Optics 2.3.5 Isolators, Circulators and Faraday Rotation Mirrors2.3.6 Fibre Bragg Gratings 2.3.7 Modulators 2.3.7.1 Acousto-optic modulators 2.3.7.2 Electro-optic modulators 2.3.8 Switches 2.3.9 Polarisation Controllers 2.3.10 Connectors and Splices 2.3.11 Detectors 2.3.12 Other Symbols References Chapter 3 Principles of Optical Time-Domain Reflectometry (OTDR) for Distributed Sensing 3.1 Optical Time-Domain Reflectometry 3.1.1 Single-Ended Measurement 3.1.2 Double-Ended Measurement 3.1.3 Capture Fraction 3.1.4 Coherence Effects 3.1.5 Signal Levels 3.2 OTDR System Design Optical fibre technology -- Principles of optical time-domain reflectometry (OTDR) for distributed sensing -- Raman-based distributed temperature sensors (DTSs) -- Brillouin-based distributed temperature and strain sensors -- Rayleigh backscatter : distributed vibration sensors and static measurements -- Applications of distributed temperature sensors (DTSs) -- Distributed strain sensors : practical issues, solutions and applications -- Applications of distributed vibration sensors (DVSs) -- Other distributed sensors Distributed optical fiber sensors (DOFS) are capable of revealing information about temperature, strain, vibration, pressure, or magnetic field from anywhere along the fiber. This book explains their physical principles, unique benefits, broad categories, implementation aspects, and performance criteria.