Simulation of the reflection of a high energy laser beam at the sea surface for hazard and risk analyses

• Frederic Schwenger, Adrian Azarian, and Michael Henrichsen
• received 12/26/2023; accepted 04/11/2024; posted 04/12/2024; Doc. ID 516715
• Abstract: The application of a high energy laser beam in a maritime scenario necessitates alaser safety concept to prevent injury to personnel or uninvolved third parties from uncontrolledreflections of laser light from the sea surface. Therefore, it is crucial to have knowledge of theamount and direction of reflected laser energy, which varies statistically and depends largelyon the dynamics of the wavy sea surface. These dynamics are primarily influenced by windspeed, wind direction, and fetch. An analytical model is presented for calculating the time averaged spatial intensity distribution of the laser beam reflected at the dynamic sea surface.The model also identifies the hazard areas inside which laser intensities exceed a fixed exposure limit. Furthermore, as far as we know, our model is unique in its ability to calculate the probabilities of eye-damaging glints for arbitrary observer positions, taking into account theslope statistics of gravity waves. This is a critical first step towards an extensive risk analysis.The simulation results are presented on a hemisphere of observer positions with fixed radii fromthe laser spot center. The advantage of the analytical model over our numeric (dynamic) modelis its fast computation time. A comparison of the results of our new analytical model with thoseof the previous numerical model is presented.