INTRODUCTION: Fibre optical sensors offer number of distinct advantages which makes them unique for many applications where conventional sensors are difficult or impossible to deploy or can not provide the same wealth of information. They are completely passive, hence can be used in explosive environment. Immunity to electromagnetic interference makes it ideal for microwave environment. They are resistant to high temperatures and chemically reactive environment, ideal for harsh and hostile environment. Small size makes it ideal for embedding and surface mounting. Has high degree of biocompatibility, non-intrusive nature and electromagnetic immunity, ideal for medical applications like intra-aortic balloon pumping. They can monitor a wide range of physical and chemical parameters. It has potential for very high sensitivity, range and resolution. Complete electrical insulation from high electrostatic potential and Remote operation over several km lengths without any lead sensitivity makes it ideal for deployment in boreholes or measurements in hazardous environment. Unique multiplexed and distributed sensors provide measurements at large number of points along single optical cable, ideal for minimising cable deployment and cable weight, monitoring extended structures like pipelines, dams.
Various types of sensors are Point sensors, Integrated Sensors, Quasidistributed multiplexed sensors, Distributed sensors. Examples of such sensors are Fabry-Perot sensors, Single Fibre Bragg Grating sensors, Integrated strain sensor, Intruder Pressure sensor, Strain/Force sensor, Position sensor, Temperature sensor, Deformation sensor etc.