Word: infra
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Dates: during 1960-1969
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...picture is snapped. But Dr. Gershon-Cohen, a radiologist at Albert Einstein Medical Center in Philadelphia, is the extremely careful scientist, not the temperamental artist. Borrowing a technique space researchers use to take temperature readings of Venus, he photographs the human body's surface heat with a novel infra-red camera...
...were not successful, mostly because of hastily assembled equipment. After many months of work, an improved transmitter pointed at Lincoln Laboratory from Mount Wachusett. The tiny gallium arsenide diode, only 0.01 in. in diameter, was placed precisely at the focus of a 5-in. reflecting telescope that concentrated its infra-red light into a tight bundle. On the roof of the lab, the researchers set up their receiver-the reflector of a 5-ft. war-surplus searchlight with a sensitive photocell at its focal point...
...told the men on the mountain to begin talking into a microphone and modulating the infrared beam. The response came clearly across the cold night air and was picked up by the lab-top receiver. "I'm starting now." Those words had covered 34 miles, passing over an infra-red beam that carried only .005 watt of energy. It would take 1,500 such diode beams to equal the power used by a single flashlight bulb...
...breakthrough had come as Physicist Robert J. Keyes checked on the properties of a gallium arsenide diode developed by Lincoln Lab Engineer Theodore M. Quist. A less-than-gnat-sized electronic device that generates pure infra-red light when a small direct current is passed through it, the diode turned out to have an extraordinary property: the intensity of the normally invisible infra-red beam could be easily controlled by varying the strength of the current that generates it. Keyes speculated that if his little light beam was visible at any distance, it could be modulated to carry the human...
Potential Unlimited. For hours the scientists on Mount Wachusett declaimed joyfully over the remarkable beam. Next they turned on a TV receiver, tuned in a Boston channel and retransmitted the picture to the laboratory by infra-red rays. The results were more than satisfactory...