Underwater Laser Imaging

Attenuation of light in the ocean ranges widely depending on the environment and is especially significant in optical remote sensing. Absorption of light by ocean water limits the range light can travel before being extinguished. The complex interactions of scattering light and ocean water often lead to distortions of the signal as it propagates which degrades the quality and accuracy of underwater measurements. Consequently, underwater visibility (i.e. how well an object can be seen with definition at distance) can be less than 1 [m] in turbid and murky environments such as harbors. Advancements in laser imaging systems make highly accurate measurements at further ranges than has previously been possible through temporally filtering of a modulated laser signal at frequencies as high as 1 [GHz]. Here we overview the processes affecting underwater light propagation and visibility, laser imaging systems, recent advancements in the field of underwater optical imaging, and the application of such systems.