Super-Microscope

From Berlin last week came news that technicians of Siemens & Halske Co. had developed a ''super-microscope" with a magnifying power far surpassing that of ordinary high-grade instruments. To obtain its supermagnification, the German instrument uses beams of electrons instead of waves of light.

In modern physics, beams of light are considered as particles as well as waves, and beams of electrons are considered as waves as well as particles. A microscope using visible illumination is limited in magnifying power by the wave length of light. Particles considerably smaller than the wave length escape detection because they slip through the meshes of the light waves like BB shot through a tennis net. But electrons have wave lengths 100,000 times smaller than those of light, and electrons, although they cannot be focused by a lens, can be focused by electric or magnetic fields which act on the electron beam as a lens does on light.

The idea of electronic magnification has been a live subject in physics for a decade. Foundations of the technique were laid down in Germany in 1926-27. Other work has been done in Belgium and in the U. S. by Dr. Clinton Joseph Davisson of Bell Telephone Laboratories, who won a Nobel Prize in physics last year for experimentally demonstrating the wave nature of electrons. Some years ago, Astronomer Francois Charles Henroteau of Ottawa's Dominion Observatory suggested that an electronic telescope (converting feeble starlight into electric current by means of photoelectric cells) could be built which would equal a 2,000-inch mirror telescope -- ten times bigger than the 200-inch giant now being erected on a California mountain.

In the German electronic microscope described last week, electron beams are straightened out in a magnetic coil, passed through the specimen to be studied, focused in another coil. The voltage used is 80,000. The resolving power (magnification) is 25 times greater than in visual microscopes, whereas a tenfold increase for electronic magnification had previously been considered tops.

Electrons make impressions on photographic emulsions just as light particles do. Using a magnification factor of 20,400, the Siemens & Halske scientists obtained pictures of the pus germ, Staphylococcus aureus, as big as pennies. In photographs with ordinary high-power microscopes, such germs show up pinhead-size.

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