Modern ocean exploration technologies are taking a giant leap forward thanks to the development of an innovative acoustic lens. Researchers have created a device that allows underwater drones to obtain incredibly clear images of the seabed without using bulky and energy-intensive supercomputers. For a long time, the main problem of underwater cartography remained the imperfection of sonar systems operating in conditions of extreme pressure and great depths.
Ocean Mapping Challenges and Sonar Limitations
To date, satellites have mapped 100 percent of the seabed, but the resolution of this map remains extremely low at about 1.6 kilometers. Shipboard multibeam sonars at great depths provide a resolution of only 15 to 50 meters. Scientists are convinced that the use of autonomous underwater drones makes it possible to bring measuring instruments closer to the bottom, but another obstacle arises here: to protect equipment and reduce hydrodynamic drag, sonar emitters are placed along a curved fairing. The curved shape of the dome deforms the wave front, the sound beam expands, loses power, and modern electronic correction systems require too much energy.
Innovative Acoustic Lens: Design and Principle of Operation
To solve this fundamental engineering problem, researchers calculated the nature of the distortions and created a unique physical lens that corrects the sound wave even before it passes through the fairing. This development works by analogy with how an optical system corrected the mirror of the Hubble Space Telescope. Structurally, the lens consists of concentric silicone rings, each of which contains a strictly verified ratio of tungsten microparticles. It is the addition of tungsten that changes the speed of sound propagation through the material. An important advantage is personalization: the holographic lens can be manufactured individually for the dome geometry of a specific model of an underwater vehicle.
Field Tests and Prospects for Exploring Seamounts
Laboratory and practical tests have already proven the high efficiency of the invention. The use of the lens narrows the sonar beam from an angle of over 65 degrees to 16-30 degrees. During field tests on the Jiulong River, the drone successfully detected a submerged plastic sphere at a shallow depth, while without the lens, the echo signal was completely lost in environmental reflections, and the noise level decreased by 11.98 decibels. Experts are confident that the technology will allow a detailed study of more than 100,000 seamounts with a height of over 1,000 meters, of which less than 0.1 percent have currently been studied. The next stage will be large-scale tests of the lens in real seawater.
Contradictory Data
While developers claim a radical reduction in the cost and simplification of underwater reconnaissance due to the rejection of powerful onboard computers, some independent experts express skepticism regarding the durability of silicone-tungsten composite materials in aggressive saline environments and extreme pressures at great depths. Nevertheless, the first laboratory successes and field tests on the Jiulong River confirm the viability of physical wave front correction.
