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Friday, April 6, 2018

New camera could be used for underwater exploration

Por Damian

The key to a new underwater positioning system seems to be the multi-talented mantis shrimp. Two years ago, a researcher at the University of Illinois, inspired by this underwater warrior, imitated his bulging eyes to create a camera capable of recording polarized light and better detect some types of cancer. And now that same technology might be used to develop a global submarine positioning method.

If it is specified, this could have very broad implications, from improving rescue efforts to advancing the investigation of the seas. "We are collecting a lot of information with cameras above sea level," said mechanical engineer Viktor Gruev, one of the editors of a study published recently in Science Advances, along with Samuel Powell, an engineer at Washington University. "Think about what you could do in the same way under water."

Global navigation systems depend on numerous satellites that orbit the Earth. But those radio signals cannot penetrate the water, which makes underwater navigation a costly affair of bulky equipment based on ultrasound or gravitational fields. The Department of Defense is in the midst of an effort (that will teak years) to develop a drone network to give the Navy its first submarine global positioning system.

Gruev's camera, which according to him is "similar to a GoPro", does not work without light, but offers a cheaper and more mobile solution than what exists in the market at this time. The system is based on polarized light in the water. Depending on the angle and time of day, the camera determines its location in a position within about 37 miles. Gruev says the team is still working on perfecting the system and reducing that margin.

During the development of the camera, Gruev and Powell also corrected an ancient confusion about the properties of polarized light in water. In the 1970s, Gruev said that the renowned expert Talbot Waterman, of Yale University, discovered that when light is polarized in water it does not travel uniformly in the horizontal plane as well as out of water. Waterman suggested that more research was needed, Gruev said, but over the next few decades the scientists kept thinking that the light moved horizontally. But when they used the camera to record underwater, Gruev and Powell noticed that the angles were not uniform and changed constantly. Other researchers concluded that the camera could have some problem. "But I was sure the camera worked properly," Gruev said.

Instead, Gruev guessed that the patterns were related to the location of the sun and could in fact be combined with the time to determine locations. "I asked how polarized light behaves underwater," he said, and if the physical principles of water cause light to polarize differently. It was necessary to use complex models and measurements, as well as advances in camera technology, to test their theory.