Radio age research, manufacturing, communications, broadcasting, television (1941)

fr;uti(in patterns. Many applica- tions are makinj;: use of this phe- nomenon for straight process con- trol of product and injrredients. Since an electron microscope is primarily a cathode ray tube which must be opened from time to time to atmospheric pressure to admit new specimens and photographic plates, careful consideration must be given to the vacuum system and its control. As the electron beam, used to illuminate the specimen, is rapidly absorbed and scattered b.v gas molecules, a relativel.v high vacuum must be maintained in the body of the microscope. Generally speaking, commercial and labora- tory vacuum systems are quite com- plicated, consisting of a multiplic- ity of controls, valves and pressure indicating devices. Vacuum control —"rough" pumping, final pumping, "bleeding" to atmospheric pressure and all other sequences—are con- trolled by one simple valve crank in both of the new microscopes. Since the columns—or microscopes themselves—have been designed for minimum volumes and since the columns themselves are the only portions of their respective vacuum systems requiring pumping during operation, the time required be- tween specimen changes has been kept to a ma.ximum of about one minute and a half, and no air locks or auxiliary pumps are required. Systems Are Simplified The electronic systems which control the accelerating voltage— and therefore the wavelength asso- ciated with the electron beam—and those which control the power of the electro-magnetic lenses of the new microscopes, are greatly sim- plified. For example, the Universal Microscope has only twenty-five vacuum tubes compared to the older B Microscope which had fifty-one. Tlu' Console Microscope re(iuires only fourteen tubes for its opera- lion. As a result, the new Micro- scopes require proportionately few- er circuit components and space and facilities for mounting them. All electrical and mechanical con- trols have been designed and posi- tioned for operator comfort and convenience — specimen movement, image intensity, magnification, fo- cusing, power contrt)l, camera con- trol, vacuum and circuit meters, are all within easy and convenient reach of the operator. Occupies Small Space IMechanically, the new microscope columns are greatly simplified. Clamping rings, gaskets, Sylphon bellows, etc., which are essential parts of demountable and adjust- able vacuum systems, have been re- duced to a practical minimum. Whereas the EMB Microscope em- ployed 22 Sylphon bellows, the Uni- versal Model uses seven and the Console Model only three. Most of the Sylphon bellows were elimi- nated by design simplification but in certain cases, bellows have been replaced by a recently developed type of rubber seal. These new rub- ber seals permit rotary or recipro- cating motion within the evacuated chambers and render months of continuous service without atten- tion. The Universal Microscope is in- tended for a fixed type of installa- tion. The cabinet has been designed to occupy a minimum of floor space consistent with average allowable floor loading. The instrument may be mounted against a wall or free of any partition. Power, water and forepump connections can be made by way of floor trenching or fed through the right, left or rear of the bottom skirt of the cabinet. The only accessories external to the microscope cabinet are the fore pump and line voltage stabilizer which can be installed in an adja- c;'iit room or other nearby conve- nient location. The Console Model has been de- signed for semi-portable usage. The desk type construction, whose di- nu-nsiciiis allow clear passage through a standard thirty-inch door, fulfills the requirements for occasional mobility. The Console desk houses the fore pump and all other accessories except the line voltage stabilizer, which can be mounted at any nearby convenient location. A large amount of storage space is provided by the shelving unit built into the compartments at the right and left of the kneehole of the desk. Both the Universal and Console Models of the Electron Microscope can be operated from standard socket power—110 volts. The Uni- versal Model consumes 1,500 watts and the Console Model 1.000 watts. Both instruments have vacuum sys- tems which pump their respective columns to better than one tenth micron of mercury. The Universal Microscope has a direct magnification range of from 100 to 22,000 diameters, adjustable in forty steps. The Console Model ]irovides two direct magnifications of 500 or 5,000 diameters. The pho- tographic negatives produced by either microscope must be photo- graphically enlarged to reveal all the detail present. Development Continues Each day brings new discoveries and broadens the list of applica- tions of electron microscopy. Keep- ing pace with this new science^—the science of electron microscopy—is the RCA Product Design Group, among whom are such outstanding young engineers as Dr. Robert Picard, hamuel Zollers, Frank Runge and Miss Helen Muenscher. Advance development is proceeding on other electron optical devices related to the science, and each new [jfoduct will perform new and use- ful service for mankind. Buy War Bonds [RADIO AG E II]