what are we talking about here? >> well, essentially, we're talking about a solar cell surface, which is far more efficient in collecting light because its surface is decorated with the -- with eyes of a fly, not exactly the eyes of a fly but copies of the eyes of a fly. >> in other words, the eye of a fly is particularly efficient if you're trying to create an array that you collect solar energy -- i guess this means we have to explain, solar energy is collected by having some sort of a flat surface that absorbs the sun's rays? >> that is correct. that is what most solar cell surfaces are, they are essentially flat. there is a certain amount of texturing on these surfaces. but the eye of a fly is an amazing object. try catching a fly. you will find it is difficult to do so. and the reason for that is that the fly has about 270 degrees of vision angle.