With concern to engineering structures it is of increasing importance for safety as well as for economical reasons to control, whether changes in utilization, whether aging and fatigue of materials, environmental conditions, whether time- depending response etc. might affect the material as well as the structural response as e.g. stability, safety and service-life adversely. This can be done only by measurements, based on the principles of experimental mechanics, combined with proper algorithms for data-evaluation. Application of such methods is not restricted to basic research and material testing in laboratories. They have proved to be quite useful in remote control and health monitoring of technical structures, especially of those with high risk-potentials in case of failure. They should be applied to new as well as to already existing structures in order to get reliable knowledge on the behavior of structures over the whole life-span. As yet mainly methods of electrical measuring mechanical quantities are used in a wide variety of combinations. But nowadays different optical methods are available also, which are very precise and highly reliable in the long run, relative insensible against external influences, adaptable to almost any kind of problem. An overviews on different optical methods will given.