Positron Microscopes Offer A New View of Things

A positron microscope may soon open a new window to the realm of the very small. While the view through this device would not be as finely resolved as that through its antimatter cousin, the electron microscope, it could reveal a qualitatively different landscape. Hopes for a positron microscope were boosted recently when independent groups successfully operated two such instruments, one with an especially high resolution. Both the devices are based on the reemission of positrons from a surface. James Van House and Arthur Rich of the University of Michigan, who last year also built a transmission positron microscope, have operated their reemission microscope with a resolution of 2000 nm. George Brandes and Karl Canter of Brandeis University, together with Allen Mills of AT&T Bell Labs, have constructed a reemission positron microscope of slightly different design that has a resolution of 300 nm—the limit for optical microscopes—and a magnification factor of 1150. Both groups feel that further enhancements could give the positron microscope a resolution of 1 nm. At such a resolution, the microscope could facilitate studies of crystal defects and of biological molecules.