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Adjustable diffraction gratings made of tiny artificial muscles could bring more lifelike colors to TVs and computer displays, physicists at the Swiss Federal Institute of Technology (Eidgenössische Technische Hochschule, or ETH) in Zurich, Switzerland show in the September 1 issue of Optics Letters.

In ordinary displays such as TV tubes, flat-screen LCDs, or plasma screens, each pixel is composed of three light-emitting elements, one for each of the fundamental colors red, green, and blue. The fundamental colors in each pixel are fixed, and only their amounts can change -- by adjusting the brightness of the color elements -- to create different composite colors. That way, existing displays can reproduce most visible colors, but not all. For example, current displays do not faithfully reproduce the hues of blue one can see in the sky or in the sea, says Manuel Aschwanden.

Like a rooftop antenna which grabs meter-sized radio waves and turns them (courtesy of a tuned circuit) into signals far smaller in physical extent, so the optical antenna converts visible light into an illuminating beam of much higher resolving power. For example, 800-nanometer light can produce images with a spatial resolution of no better than about 400 nanometer.