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

and magnify the infinitesimally small particles of matter, bacteria, and viruses is producing informa- tion extremely valuable to the United Nations' war effort and to America's health, science and in- dustry. This fact was brought forcefully to public attention during Novem- ber and December when the first exhibitions and demonstrations of the RCA Electron Microscope were held in Chicago and Washington, D. C. In Chicago, the instrument which, while not as versatile as the large standard model, gives the same high degree of resolution and magnification. In this small model, the electron microscope becomes available—after the war—to liter- ally hundreds of medical, univer- sity, and industrial research insti- tutions. The other development was the "stream-lining" of the large standard model to effect a 35 per cent reduction in weight, in elec- tronic tubes and in other compo- nents. Operation was substantially THE NEW DESK-SIZE RCA ELECTRON MICROSCOPE, AS IT WILL APPEAR IN ITS COM- MERCIAL DESIGN. IT WILL BE BUILT BY THE RCA VICTOR DIVISION. was the feature exhibit at the joint meeting of the National Industrial Chemical Conference and the Chi- cago Section, American Chemical Society. More than 24,000 persons registered at this conference. In Washington, approximately 3,500 high Government officials, repre- sentatives of the Army and Navy, the diplomatic corps, and leading educators and scientists saw the microscope as guests of RCA Lab- oratories. Two outstanding developments in the design of the microscope were announced at Chicago. The first one was a small desk-type instrument. improved, both as to simplicity and efficiency. Since practically all of the work being done today with the RCA Electron Microscope is directly re- lated to the war, secrecy guards most of its accomplishments. How- ever, it is permissible to review the progress made in developing the techniiiue of the instrument's ap- plication. It is also possible to show how widely distributed the micro- .scope is among hospitals, univer- sities, research laboratories and industry. The month of December, 19-12, marked the second anniversary of the delivery of the first commercial electron microscope. This instru- ment was delivered to the American Cyanamid Company's research lab- oratories in Stanford. Conn., and is known as the RCA Type B Elec- tron Microscope, or the standard model. Since that date, forty-six of these instruments have been delivered. Of this number, nine have been ex- ported to our Allies and the re- mainder were installed in labora- tories in this country. Soon after the first instruments were placed into use, it was realized with the higher magnification avail- able that necessarily the field to be examined was limited. Therefore, it became increasingly difficult to interpret the results obtained with increased magnification. A prac- tical example of such a case was the study of the calcium carbonate where the calcium carbonate (arag- onite) was photographed at a total magnification of 85,000 times. I'lion examination of this micrograph, it is easily seen that the separate crys- tals are elongated, porous and quite uniform in shape. However, studies of this same field at low magnifica- tion with the light microscope showed what appeared to be large particles. Therefore, it was as- sumed that there must be some value of intermediate magnification that would tell the full story. As a result of these conclusions, ex- perimenters expanded the range of the electron microscope to cover the region from approximately 200 di- ameters to 20.000 diameters by varying the length of the specimen holder. These pioneers of electron microscopy soon discovered that the seemingly large particles visible un- der the light microscope were actu- ally a "Burr" cluster of the crystals visible in the electron micrograph taken at 85,000 diameters. The work of these men and many others soon established the fact that high magnification in itself was not the true answer, but that even low mag- nification must be covered in order to obtain a comprehensible result. The present instruments, therefore, are capable of magnifications below 1,000 diameters and, by minor ad- justments to the instrument, can be carried below 600 diameters. The magnetic lens used in the [16 RADIO AGE