The latest adv­ance in the war against hidden bombs, lurking cockroaches and illegal immigr­ants comes straight from the floor of the ocean. Lobsters possess one of the most unique vision systems in the animal world, and researchers are working on adapting that system to X-ray scanners that will make steel walls about as opaque as tissue paper.

X-rays are a form of electromagnetic energy. The spectrum of electromagnetic energy also includes radio waves and visible light. Some materials absorb X-rays, others reflect them and others let them pass through, refracting the beams so that they bend. Refracted X-rays exit the material at a different angle than the one at which they hit.

A typical X-ray system uses an X-ray generator, which produces a beam of X-rays, and a detection medium (an optic system). To make an image, X-rays are fired at an object. Some of the X-rays pass through the object and are refracted. Other X-ra­ys are absorbed completely, and some are reflected. The detection medium "sees" the X-rays that pass through the object.

This system works well, but it's not ideal. First, the refracted X-rays are bending at different angles, so it's difficult for the optics to effectively collect and focus them. Second, since the refraction makes the system less efficient, the X-rays have to be pretty high-powered in order for the optics to gather enough energy to form an image. And high-power X-rays aren't the safest thing in the world.

The eyes of humans and other animals also rely on refraction. But not lobsters. The way a lobster perceives light is different, and it's a visual system that's almost entirely unique to crustaceans. So what makes lobster vision so special? Next, find out why the eye of a lobster is a lesson in visual efficiency.