Measuring and modeling the air-sea interface and its impact on FSO systems

The ocean surface has considerable impact on air-to-sea (or sea-to-air) imaging, lidar scanning, and optical communication. This surface is rarely smooth, of course, especially in the littoral region (due to a variety of impacts, from wind to ship wakes, etc.). Most current and previous methods for addressing this roughness and its impact on optical propagation are either fully statistical, totally theoretical, or are "mixed methods" based on a combination of statistical models and parametric-based physical models (our preferred approach). To better understand the statistical nature of the sea surface, experiments were performed in a 50 foot long wave tank capable of not only producing large scale, multi-frequency waves, but also wind driven waves over a range of velocities. High speed imaging (i.e., Photron FASTCAM Mini series ^® ) of laser beam projection as well as spatial distribution of surface glint, scanned laser velocimetry measurements of the surface, and deflection statistics of the doubled Nd:YAG (532 nm) beam will all be utilized to produce statistical models of sea surface perturbations under various wind loads and larger scale wave forcing. These data, combined with our mixed model, will help us to measure, analyze, and understand the shape of the sea surface and assess its subsequent impact on optical propagation and specifically on aerial to underwater FSO communication links.