Researchers from the University of Bristol (Bristol, England) in collaboration with colleagues at the University of Maryland, Baltimore College (UMBC; Baltimore, MD) and the University of Queensland (Australia), according to a recent story in Nature Photonics, have uncovered the science behind the complex vision systems of mantis shrimps, which can see in 12 colors (humans see in three) and can distinguish between different forms of polarized light (see also "Biomimetic designs advance optical performance" and "Thin-film technique mimics butterfly wings").
Special light-sensitive cells in mantis shrimp eyes act as quarter-wave plates, which can rotate the plane of the oscillations (the polarization) of a light wave as it travels through it. This capability makes it possible for mantis shrimps to convert linearly polarized light to circularly polarized light and vice versa. Manmade quarter-wave plates perform this essential function in CD and DVD players and in circular polarizing filters for cameras. However, these artificial devices only tend to work well for one color of light while the natural mechanism in the mantis shrimp's eyes works almost perfectly across the whole visible spectrum—from near-ultraviolet to infrared.
Nicholas Roberts, lead author of the paper said, "Our work reveals for the first time the unique design and mechanism of the quarter-wave plate in the mantis shrimp's eye. It really is exceptional—out-performing anything we humans have so far been able to create. Exactly why the mantis shrimp needs such exquisite sensitivity to circularly polarized light isn't clear. "What's particularly exciting is how beautifully simple it is," Roberts continued. "This natural mechanism, comprised of cell membranes rolled into tubes, completely outperforms synthetic designs. It could help us make better optical devices in the future using liquid crystals that have been chemically engineered to mimic the properties of the cells in the mantis shrimp's eye."
For the full story, go to http://www.bristol.ac.uk/news/2009/6591.html.