FULAS: high energy laser source for future LIDAR applications

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For atmospheric LIDAR instruments in space, a manifold of scientific applications exists. But due to the lack of high energy laser sources providing the performance, reliability and lifetime necessary to operate such instruments in space, realization is currently seen as still very critical in the community. To overcome this, the FULAS (Future LASer Technology) project has been initiated by ESA in cooperation with the German space agency (DLR), to develop and built a technology demonstrator and to verify its suitability for potential space missions. In order to cover the common need of possible future lidar missions, requirements for a generic laser source had been defined to achieve maximum usability of the laser concept and technology for future LIDAR missions. For definition of the baseline requirements, requirements of different potential LIDAR missions for Earth Observation have been evaluated. Depending on the mission, different types of lidar principles, e.g. Doppler wind lidar, backscatter lidar or DIAL, are required which need different kinds of laser transmitters (e.g. emitting single or double pulse, operating in burst mode, operating at different wavelength and pulse energy). Common for most of them is the need of a stabilized high quality and high energy laser source which can be based on a common solid state laser platform, if necessary in combination with suitable external frequency conversion to provide the required wavelength. The main goal of the design concept of FULAS is to get versatile technology building blocks. Therefore, beside the predefined nominal operation requirements (close to the specifications of the ATLID Atmospheric LIDAR of the Earth Care mission), the flexibility of the design to be adapted and customized for manifold potential future LIDAR missions will be demonstrated. One of the main issues with respect to lifetime and reliability for high energy lasers in space is the risk of degradation of optical coatings. The main focus here is on effects by Laser-Induced-Contamination (LIC) wherefore LIC risk mitigation is a major design criterion, demanding development of several innovative technology solutions to reach the design goal to reduce the amount of organic materials to close to zero. Currently, the presented FULAS technology demonstrator is in construction phase, to be operable and ready for extensive testing begin of 2015. The technology will also be the heart of the Methane Remote Sensing Lidar Mission (MERLIN) [3],[4] (DLR/CNES, currently in Phase B).