Experiments to investigate the atmospheric propagation of laser radiation are performed with cw and pulsed lasers at different wavelengths and beam qualities. Average power data range from a few mW to 10 kW. The long-distance laser performance depends on different atmospheric phenomena: The varying atmospheric transmissivity due to different weather conditions and the optical turbulence due to random processes in the atmosphere. The limited atmospheric transmissivity causes the attenuation of the laser signal at the receiver. The optical turbulence induces scintillations and phase deformations and lead to additional beam spread and beam wander.
Numerical studies accompany the propagation experiments performed on the optical test range. In-house developed numerical codes are applied for the theoretical foundation of the measured propagation processes and for assessment and scaling tasks. The numerical codes depict the optical turbulence by means of the phase-screen approximations and make use of FFT methods for the calculation. Numerical and experimental studies complement each other in the description of the atmospheric propagation.
Moreover, the simulations allow the scaling of the experimentally confirmed results for challenges of extended range and/or extreme environmental conditions. The obtained data represent the basis for calculations in cross-departmental collaboration like imaging and tracking, long-range laser effectors, or space situation awareness. The propagation experiments provide criteria numbers for the system design and system assessment and build the basis for the conception and characterisation of future system solutions.