Extended range underwater imaging using a time varying intensity (TVI) approach

A system based on the time-varying intensity (TVI) approach was built in the early 1970´s at the Scripps Visibility Laboratory and experimental data collected by this prototype system showed an imaging capability of between 15 and 20 attenuation lengths at 640 nm. Researchers at the Naval Air Systems Command have developed an updated version of this original system with state-of-the-art components. This new TVI system uses a modulated laser illuminator to convey information about the scan to the distant receiver instead of using a separate optical trigger as was used in the original system. Laboratory water tank experiments were conducted with a prototype modulated TVI system to evaluate the effect of system and environmental variables on the system performance. In parallel with the experiments, an interactive computer simulation was developed to help evaluate the effect of the many variables on the TVI performance. Results from experiments and simulations will be discussed and compared.