3. ENGINEERING APPLICATIONS Telecommunication Long Distance Communication Handle large number of channels Signalling purposes Computer Networks Connecting computers in a topology Connecting peripherals with computers Sophisticated multibeam radars – processing transmitted signals Cable Television Replace copper wires with optical fibres Delay Lines Microwave signal processing – no attenuation of signal

4. INDUSTRIAL & MEDICAL APPLICATIONS Endoscopes Pressure, temperature sensors Linking remote sensor and monitoring station

5. FIBRE OPTIC SENSORS Optical sensor is a transducer which converts any form of a signal to an optical signal in the measurable form. Optical Source Modulation Zone Optical Detector Transmitting Fibre Receiving Fibre

6. TYPES OF SENSORS INTRINSIC or ACTIVE SENSORS Physical parameter to be sensed acts directly on the fibre to produce changes in the transmission characteristics Eg. Pressure and liquid level sensors EXTRINSIC or PASSIVE SENSORS Separate sensing element is used and the optical fibre is a waveguide. Eg. Displacement and laser Doppler velocimeter sensors