The focal length of a lens means that a camera has to have a certain thickness – or so we might think. Insect eyes show that this need not be the case: A camera chip based on the compound-eye principle can be used for person recognition and is as thin as paper.
If people were insects, books on optics would certainly look different. The camera illustrated as the technical equivalent next to a cross-section of the eye with just one lens, one iris and one retina would not be of the conventional type. A compound camera would have many hundreds of individual eyes. Each light-sensitive unit, consisting of a lens and a photocell, would capture a narrow segment of the environment. All the images together form the complete picture. An insect’s compound eye will never achieve a particularly high optical resolution, but the principle according to which it registers images does possess some advantages, and if these were incorporated in a camera it would be very flat and could cover a wide field of view.
It was precisely these advantages which inspired research scientists at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF to develop their ultra-flat camera system. “Our latest prototypes are thinner than 0.4 millimeters,” emphasizes Andreas Bräuer, who is in charge of the Microoptics unit in Jena. “You can gain a real sense of how thin that is by picking up three sheets of carbon paper between your fingers.” Cameras incorporating conventional “human-eye” optics – such as those used in mobile phones – are at best no thinner than seven millimeters.