The main requirement for an underwater salvage system is sufficient resolution to allow some form of object recognition. This feature is extremely important in deep water salvage where it is extremely expensive to use manned submersibles or hard suited divers to examine surface features or to conduct sub-bottom surveys. When sufficient detail for recognition is a major concern, high resolution acoustic imaging systems have proved to be an important factor in waters where the visibility is limited to a range such that underwater light based cameras cannot be used. These imaging systems operate over narrow frequency bands and at high frequencies to enable the sub-degree angular resolution necessary to generate high resolution images. The most effective designs use acoustic mirrors. They are capable of resolving slightly better than ½ of an inch at a range of 10 feet. There are two major deficiencies in the available systems. First , these systems are two dimensional imagers and can only provide a pseudo three dimensional image of a surface from an oblique angle and cannot pick out an object embedded in the surface. Second, the frequencies used do not penetrate most sea floor materials; therefore, objects buried beneath the bottom cannot be detected. In addition, in order to be effective a sub-bottom SONAR must be capable of operating over a wide frequency range. The standard acoustic lens based systems are designed to operate effectively over at most one octave in frequency. This is well below the 4 to 5 octaves needed for sub-bottom detailing.

       On the other hand, there are many available sub-bottom profiling systems. These systems are capable of penetrating the bottom for many feet; however, they have limited spatial resolution. While the depth resolution is sometimes in the inch range, the horizontal resolution is usually worse than a foot and more often above 10 feet. This is primarily due to the angular spread of the sound beam. The difficulty in producing a narrow beamed sound pattern increases as the sound frequency decreases. On the other hand, bottom penetration improves dramatically as the sound frequency is decreased. Because of their design, available sub-bottom profiling systems are not capable of producing the high resolution images needed for economical underwater salvage.

       UnderSea Recovery Corporation is currently designing a catadioptric acoustic imaging system that will overcome both the bandwidth limitations and the two dimensional limits of the standard systems. This system will employ both rigid (hard) and pressure-release (soft) surfaces in addition to acoustic lenses to create a system capable of generating and receiving narrow angle sound patterns with reduced side-lobes. The system will be segmented in frequency bands to allow operation over several octaves in frequency. A two dimensional sensor array will receive the scattered sound image information. This image information will be analyzed to provide not only the location but also the acoustic signature of the object. Using this type of system high resolution three dimensional sub-bottom images can be constructed. This catadioptric system can be deployed on a ROV for deep water search scenarios.

      This Web Site is currently under construction. Information is currently being added. If you have any questions please contact: info@unsr.com