Researchers from the University of Illinois recently developed an underwater GPS by using polarization information (how light gets reflected or absorbed) that was collected with a camera which mimics the eyes of the mantis shrimp. The findings were published in Science Advances and is the first demonstration of a submerged GPS that uses polarization properties to analyze underwater light. Applications could include marine navigation and developing a better understanding of the migratory behavior of marine animals.
The Mantis Cam, which is named after a type of shrimp that inspired its design, takes advantage of how light bends, or refracts, when it passes through the surface of the water, and bounces from particles and water molecules. When the team analyzed data from different locations around the globe, they observed that the polarization patterns were constantly changing as a result of the sun's position relative to the place where the recordings were collected.
This led to an understanding that using underwater polarization patterns to estimate the sun's heading and elevation angle allowed them to calculate GPS coordinates by knowing the date and time of the filming. They found that this method allowed for identifying global positions to within 38 miles.
The technology could provide new ways for people and robots to navigate underwater better using visual cues from polarized light. More cost-effective remote sensing or monitoring could be another application for studying migratory habits and the effects of ocean pollution.
Image Credit: University of Illinois News Bureau (https://news.illinois.edu/view/6367/566077#image-1)