The number of safety relevant engineering applications in which novel and lightweight materials or new structures are used is increasing world-wide. Examples are bridges, dams, tunnels, oil-downholes, and others. They require surveillance in order to monitor load history, to detect internal structural weaknesses, to significantly enhance safety and finally to increase ecological and economical benefit. Development of a monitoring technology which is affordable and can be installed in new or existing infrastructure will improve safety, reliability, comfort, energy efficiency, and running costs. For new structures or one step towards the realization of this idea is the integration of sensors during construction into important or critical elements to be surveyed. For adaptive materials and systems optical fiber sensors can provide the required sensory system.
Beneath others, main parameters of interest are often pressure, strain, and temperature changes during operation. Electronic pressure sensors, resistance strain gauges and thermoelectrical sensors are the conventional methods of choice. However, more and more fiber optical sensors have been applicated, especially in harsh environments where electrical sensors often fail early. The fiber's shape, its immunity to electromagnetic fields, the possibility to distribute several sensors in one fiber make them very attractive for sensor applications.
Fiber optical sensing technology can be a key element for long-term performance monitoring, and process control. The measurements should be reliable over the required monitoring time. Therefore, sensor packaging / embedding, durability considerations as well as accelerated aging tests and lifetime models are important when discussing optical fiber sensors like Fabry-Perots, Bragg gratings and others.