Telescopic Short Cut

Stargazers, as they wait for newer, bigger telescopes to be built, long for a short cut to a better look through the light years at unexplored outer space. Last week University of Chicago Astronomer William A. Hiltner completed laboratory tests on a new "image-converter" that may increase telescopic visibility a hundredfold.

Used in the Army's World War II snooperscopes, the image-converter is essentially a booster for light. In a vacuum tube, photons of light strike a cesium-antimony photocathode, which in turn gives off high-speed electrons. The electrons are accelerated through an electric field, hit a sensitive "retina" screen or a photographic plate, and etch out a crisp picture. Used in celestial photography, the image-converter proved impractical. Reason: water molecules in the photographic emulsion reacted with the cesium, destroyed the unshielded photocathode.

Astronomer Hiltner found a physicist's solution to the problem. At the university's Yerkes Observatory, he installed an aluminum shield, only four-millionths of an inch thick, between the photocathode and the photographic plate. The fast electrons passed right through the shield like light through a window; the foil prevented the water molecules from destroying the vulnerable cesium, hence the light booster could operate indefinitely.

Although Hiltner has yet to put his gadget on a telescope, he and his Yerkes colleagues are sure that it means a revolution in stargazing. At present, astronomers using the world's biggest (200 in., $6.5 million) telescope at Mt. Palomar, Calif, can record, i.e., photograph, galaxies 1 to 2 billion light-years away. With Hiltner's gadget boosting the light intake many times, astronomers may find aging galaxies even farther out and in richer detail than ever before, at a fraction ($180) of the huge costs involved in building bigger telescopes.

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