Rounding out an insect-eye view.

A new humanmade version of an insect's compound eye could perform like the real thing. Because of its pinhead size and anticipated low cost, the eye is promising for many applications, its inventors say. Those uses include miniature surveillance cameras and medical endoscopes.

Flies, bees, and other insects see with faceted eyes made of thousands of lens-capped, light-guiding columns called ommatidia, says bioengineer Luke P. Lee of the University of California, Berkeley. He and his Berkeley colleagues Ki-Hun Jeong and Jaeyoun Kim created an artificial, dome-shaped eye with faux ommatidia. They unveiled the eye in the April 28 Science.

To build the new eye, the Berkeley researchers first made a hemisphere 2.5 millimeters in diameter of ultraviolet-sensitive resin with its surface molded into thousands of microlenses. Doing so required both standard microchip-fabrication methods and an unconventional means of forming microstructure templates out of soft plastic, Lee notes.

Next, the Berkeley researchers exposed the resinous hemisphere to ultraviolet light, which the microlenses focused inward as narrow beams. As those beams penetrated the block, resin polymerized along the radiation's path.

The resulting columns of hardened and optically altered material inside the hemisphere act as ommatidia because they guide light along a precise line from each lens, Lee says. However, the eye needs further tweaking to capture images, he notes. Its ommatidia must extend deeper and meet up with an array of microelectronic photosensors.--P.W.