File:Bell telephone magazine (1922) (14752924771).jpg

Identifier: belltelephonemag4344amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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nique in microscopy de-veloped at Bell Telephone Laboratories. Thetechnique enables scientists to study internalcrystal defects in semiconductor diodes with-out damaging the specimens or using specialtreatments. 60 The basic equipment used is a standardscanning electron microprobe. It produces afinely-focused electron beam that probes thespecimens at a depth determined by the en-ergy of the beam—the greater the energy,the deeper the beam penetration. When the scanning electron beam probesthe p-n junction of a semiconductor diode,the diode produces a response current. Thiscurrent is amplified and fed to a cathode raytube that displays it as a map-like picture.Crystal defects usually cause a reduction inresponse current and appear as dark regionsin the picture. It is believed that this technique will be avaluable tool in microanalysis, supplementingpresent scanning electron microprobes. Photomicroi^niphs showing crystal imperfec-tions made possible by new Bell Labora-tories technique.
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We dug and refilled a 4000-mile trench to protect 9300 communications circuits against disaster We split the continent with a trench fourfeet deep to give the United States its firstblast-resistant coasttocoast undergroundcommunications cable system. More than four years ago when the firstof 2500 giant reels of coaxial cable startedunrolling in New York State, we began animportant project that will give added pro-tection to the nations vital communica-tions. Today, 9300 circuits—available for voice,data, teletypewriter, telephoto—are includedon this route. It stretches across 19 statesand has 950 buried reinforced concrete re-peater (or amplifying) stations. Spotted strategically along the routeabout 50 feet below ground level are 11manned test centers. Also of reinforced con-crete, they have automatic air filtration andventilation and living quarters stocked withemergency food and water. This vital transcontinental link will servethe needs of government agencies, busi-nesses and

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