6. Conclusion

The experiments presented here illustrate the value of optics in underwater imaging. Several imaging principles can be envisaged, depending on the application , but the principle proposed here gives priority to range without compromising resolution too much. On Lambertian echoes, the range is 150 m for the type of water used (c = 0.1 m ^-1 ); at this distance, angular resolution would be a few centimetres. This kind of performance would make it possible to identify targets optically at medium range, complementing existing imaging sonars.

In addition to our own experiments, work carried...