Tinyvision

During an electronics experiment at Albuquerque's Sandia Laboratories, a scientist accidentally sent a pulse of electricity through a dime-sized ceramic chip. He watched in amazement as the ceramic abruptly changed color. Now, after four years of study and further tests, Sandia experimenters believe that the chance observation may have spawned an entirely new technology that will eventually have wide applications in computers and communications.

In Philadelphia at a meeting of the American Ceramic Society, Ceramist Gene Haertling and Electrical Engineer Cecil Land explained the secret of the ce-ramic's unusual behavior. Tiny crystals in the ceramic--packed some 100 million to the square inch--respond to electric voltage much as iron filings align themselves in a magnetic field. High voltage causes many of the crystals to change their orientation; low voltage affects only a few. By reversing the voltage, the change can be erased. That accounts for the color change; the ceramic is transparent only to a narrow range of light frequencies, or colors, at one time.

Telegrapher's Key. When the degree of orientation of its crystals is changed, the ceramic becomes opaque to the original color, but allows another color to pass through. Sandwiching a ceramic plate between two polarizing disks and applying different voltages in sequence, Haertling and Land found that they could precisely control the color the ceramic would transmit.

With these properties, the Sandia scientists say, the ceramic will be useful in computers. Because its crystal orientation is determined by the last applied voltage, it is ideal for memory storage; its light-transmitting qualities can be used for computer read-outs and displays. Placed in front of a laser, the ceramic filter can block off the laser beam or let it through, depending on the amount of voltage applied. It can control the laser beam, much as a telegrapher's key modulates a radio wave, thus transmitting information.

Other scientists see an even more exciting application: color television sets the size of transistor radios. Using a hundred times less voltage than conventional sets, tiny battery-powered ceramic TV screens would show purer colors than conventional sets, without generating hazardous X rays. They could also be used as an animated color transparency. Placed in a light projector, they could flash large TV images against a movie screen or even a plain white wall.

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