Shrimp Eyes That Polarize
BRISTOL, UK, Oct. 26, 2009 – Mantis shrimp, found on the Great Barrier Reef in Australia, have the most remarkable and complex vision systems known to science. They can see in 12 colors – humans see in only three – and can distinguish between different forms of polarized light. According to a new study from the University of Bristol, these shrimp eyes are inspiring innovation in next-generation optical devices.
Special light-sensitive cells in mantis shrimp eyes act as quarter-wave plates, which can rotate the plane of the oscillations, or polarization, of a light wave as it travels through it. This capability makes it possible for the mantis shrimp to convert linearly polarized light to circularly polarized light and vice versa. Man-made quarter-wave plates perform this essential function in CD and DVD players and in circular polarizing filters for cameras.
The mantis shrimp, Odontodactylus scyllarus. (Image: Roy Caldwell)
These artificial devices, however, tend to work well for only 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.
“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 – outperforming anything we humans have so far been able to create,” said Dr. Nicholas Roberts, lead author of the paper, which appears in Nature Photonics.
Exactly why the mantis shrimp needs such exquisite sensitivity to circularly polarized light is not clear. However, polarization vision is used by animals for sexual signaling or secret communication that avoids the attention of other animals, especially predators. It also could assist in the finding and catching of prey by improving the clarity of images underwater.
“What’s particularly exciting is how beautifully simple it is,” Roberts added. “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.”
This wouldn’t be the first time humans have looked to the natural world for new ideas. For example, the lobster’s compound eye recently inspired the design of an x-ray detector for an astronomical telescope.
The mantis shrimp research was conducted at the University of Bristol’s School of Biological Sciences in collaboration with colleagues at the University of Maryland, Baltimore County, and at the University of Queensland, Australia.
For more information, visit: www.bristol.ac.uk
- circularly polarized light
- A light beam whose electric vectors can be broken into two perpendicular elements that have equal amplitudes and that differ in phase by l/4 wavelength.
- The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
- x-ray detector
- One of various types of fluorescent screens used to detect x-ray radiation. Photographic film is mildly sensitive to x-rays, but much more sensitive to light. Hence, in photographing x-ray shadowgraphs, it is common practice to compress the film between two fluorescent screens and so have the advantage of the film's natural sensitivity.
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