National Geographic : 1966 Dec
dust all interfere with the output of most lasers. The answer-perhaps decades away may be light-carrying pipes to replace today's coaxial cables and microwave relays. In space and underwater communications, lasers promise earlier use. Light can move unhampered in space, carrying messages from one spacecraft to another, or to earth. Mar iner 4, using radio telemetry, sent pictures of Mars to earth on July 14, 1965, at the rate of 81/3 "bits" of information a second. So weak was this radio transmission, because of the vast distance, that each picture took more than eight hours to form. Laser light could do the job a million times faster. Argon Laser Lights Ocean Depths Submarines are already testing the potent blue-green light of argon lasers, which may pierce as much as 2,000 feet of stygian ocean water to illuminate sea bottoms or to send messages up to satellites for rebroadcast to land or to other submarines. The lost submarine Thresher and the lost hydrogen bomb off Palomares, Spain, might have come to light much sooner under the glare of the argon laser, had it been available. At this point, to speak of a laser eraser may sound faintly ridiculous. Yet Dr. Schawlow (below) is patenting such a device. Its very weak beam literally burns away the black, heat-absorbing pigment of a typed character without even scorching the white heat-reflect ing paper beneath. Will it sell? Dr. Schawlow just laughs, but he adds: "Don't forget-there must be five million typewriters manned by five million secretaries who can't spell!" All of which prompted the Electronics Weekly of London to say: "With all the talk about death rays, it's nice to know that the Americans have decided the laser can be used to erase typing errors. It gives a less frightening meaning to the verb, 'to rub out.'" From death ray to eraser-that's a long jump. But if anything can make it, the laser, with its infinite magic, will. THE END Martian ray guns in the comic strips look and act much like this "toy" laser built by Dr. Arthur L. Schawlow, a pioneer in laser research. For a classroom demonstration, Dr. Schawlow fires the beam through two balloons, a blue one inside a clear one. Transparent rubber allows the beam to pass through, but the darker balloon, absorbing the light and heat, explodes. Dr. Schawlow heads the physics department at Stanford University. EKTACHROMEBY JACK FIELDS n NG.S .