Composite materials combine the advantages of lightweight and high strength. This is in particular of interest for the development of large constructions e.g. aircraft, space applications, wind turbines etc. One of the shortcomings of using composite materials is the complex nature of the failure mechanisms which makes it difficult to predict the remaining lifetime. Therefore, condition and health monitoring are important for using composite materials for the critical parts of a construction. Different types of sensors are used to monitor composite structures. These include ultrasonic, thermography, shearography and fiber optics. Optical fiber sensors can be surface mounted or embedded in the composite construction to provide the unique advantage of in-operation measurement of mechanical strain and other parameters of interest. This is identified as a promising technology for Structural Health Monitoring (SHM) or Prognostic Health Monitoring (PHM) of composite constructions. Among the different fiber optic sensing technologies, Fiber Bragg Grating (FBG) sensors are the most mature and widely used ones. FBG sensors can be realized in an array configuration with many FBGs in a single optical fiber. In the current project, different aspects of using embedded FBG for composite wind turbine monitoring are investigated. The demonstration of using FBG sensor array for temperature and strain sensing and monitoring of a 5.8 m long scale model of a glass fiber monopile is investigated. The results indicate that the embedded FBGs successfully show the temperature increase during curing of the resin. During the static and dynamic tests, the embedded FBG sensors provided accurate monitoring.@en

This paper presents the activities performed by TNO in the field of Space Laser Communication Terminals for high-volume low cost applications, and its plans for the further development of the required technologies for space terminals with particular emphasis on highly reliable, high performance, cost effective terminals.

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To overcome data rate limitations of RF communication links with satellites, TNO and DLR envision optical free-space communication feeder links for next generation high throughput satellites. This paper provides a feasibility assessment of such links and the technology needed. The main results of the link budget and the turbulence modeling of terabit/s optical links are presented. Based on these parameters, requirements and status of the link-subsystems are discussed, and a roadmap is presented, aimed at achieving terabit per second optical feeder links.

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TNO and DLR envision optical free-space communication between ground stations and geostationary telecommunication satellites to replace the traditional RF links for the next generation of Very High Throughput Satellites. To mitigate atmospheric turbulence, an Adaptive Optics (AO) system will be used. TNO and DLR are developing breadboards to validate Terabit/s communication links using an AO system. In this paper the breadboard activities and first results of the sub-systems will be presented. Performance of these subsystems will be evaluated for viability of terabit/s optical feeder links.

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