Magnifying in 3-D

Few tools have proved more valuable to research scientists than the scanning electron microscope. Magnifying their targets 50,000 times or more, these instruments have explored so deeply into the heart of matter that they can distinguish features only 100 atoms in diameter. Yet for all their sharp-eyed versatility, the microscopes have a serious drawback: they have such a large depth of field that in their two-dimensional pictures it is often difficult to distinguish cracks from ridges or pits from lumps.

Now a scientist at Canada's Ontario Research Foundation has found a convenient way to overcome the microscope's handicap; Physicist Eric J. Chatfield has devised an adapter system that enables the electron-microscope user to get three-dimensional images. His optical stereo, which he developed at a cost of only $25,000--less than the price of a typical electron-microscope--operates on an ingenious yet simple principle reminiscent of Hollywood's experiments with 3-D movies in the 1950s.

To obtain the two views that are necessary to create a three-dimensional picture, Chatfield added an extra magnetic coil to the electron microscope. The coil deflects the microscope's electron beam as it scans a target so that the microscope actually looks at the same object from two different angles. The separate images are fed into an ordinary color-TV set, which displays one view in red and the other in green; the set's blue circuitry, ordinarily needed to give the viewer a full spectrum of colors, is disconnected. When a viewer looks at the screen while wearing glasses that have one red and one green lens, he sees a different picture with each eye and they are merged together by his brain into a 3-D image.

The stereo system is so effective that the Canadian subsidiary of Britain's Cambridge Instruments Ltd., the world's leading manufacturer of scanning electron microscopes, plans to market the Chatfield 3-D adapter in the near future for about $6,500 (the microscopes themselves run from $40,000 to $80,000). Chatfield's new technique might even be based on a bigger scale--as the basis for 3-D television.

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