1. Comparison of underwater optical and acoustic detection

Table 1 provides a brief comparison of the physical properties and technical characteristics of acoustic and optical investigation systems.

This comparison highlights the following points.

• Propagation efficiency is more variable in optics than in acoustics. The clarity of the waters in the geographical area of interest therefore strongly conditions the design and role of the underwater optical detection systems intended to work there.

• On average, attenuation is much greater in optics than in acoustics. Thus, the attenuation of the clearest water : $c=\mathrm{0,03}{\text{ m}}^{-1}\iff {\text{a}}_{\text{o}}=130\text{ dB/km}$...