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Examples presented in this paper show that the fiber optic technology is now ready for civil engineering applications. Manufacturing of two displacement sensors and reading unit has started. The short sensors (0.2 to 2 m) are ideal for monitoring structures; they work as strain transducers and can be seen as replacement for other sensors like resistive or vibrating wire gages. However, they do not give a local value of the strain, but rather an average over the length of the sensor. The long sensors (2 m and more) can be seen as extensometers and are ideal for monitoring geostructures (walls, foundations, etc.), where the relative displacement of two distant points is to be measured. They can replace the conventional Invar rod type of mechanical extensometer or even the more sophisticated sliding micrometer. The system itself permits repeated disconnections without loss of accuracy. Temperature effects or change in the fiber characteristic with time is automatically compensated by the reference fiber of the sensor. Although some more testing is needed, this system is thought to be adequate for long time measurement of civil engineering structures.