Light & Color

Rainbow Edges in a Lens

RAINBOW EDGES IN A LENS demonstrates a phenomenon that has always been a problem for astronomers and camera makers—the tendency of lenses to make rainbows out of white light. This defect in lenses is called "chromatic aberration" and occurs because the edges of a lens are prism shaped and, like a prism, disperse the colors in white light. Blue light is bent most and therefore focuses closer to the lens than red light.