NSF PR 97-6 - February 5, 1997
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Scientists Correct Microscope "Vision Problem"
Faulty human eyesight can be corrected with glasses,
but it's a different matter to fix vision problems
that afflict instruments used by scientists who explore
the microcosmos. Two Oregon scientists conducting
research with National Science Foundation (NSF)-support,
however, have found a way to do it. As with many problems
in human eyesight, the culprit in the world of microscopes
is the lens.
In devices such as electron microscopes that display
highly magnified images of specimens, a beam of electrons
passes through a focusing lens. In doing so, the beam
suffers two kinds of distortions: chromatic and spherical.
These aberrations limit the devices' resolving power.
"But now we have developed a new tool to correct the
aberrations," says O. Hayes Griffith, a University
of Oregon scientist who collaborated on the investigation
with Portland State University physicist Gertrude
Rempfer. It was supported by NSF's division of biological
infrastructure. Griffith, Rempfer and an interdisciplinary
team of Oregon scientists used an electron mirror
to cancel the unwanted aberrations caused by the lens.
The improvement, described in the January/February
issue of Microscopy and Microanalysis,
will lead to practical applications such as reduced
size for miniature electron probes and greater resolving
power for instruments designed for use in the world
of the very small.
"The most immediate application will be to emission
electron microscopes, particularly those that will
be built to equip new synchrotron light source facilities
such as the Advanced Light Source in Berkeley and
the Photon Factory in Japan," Griffith says. "These
multimillion-dollar ring-shaped particle accelerators
produce high intensity light. This light is used to
study properties of surfaces. Improved electron optics
are necessary to realize the full potential of the
synchrotron facilities."
Scientists believe the increased intensity of a synchrotron
light source provides new opportunities to study silicon,
polymer, biological and catalytic surfaces.
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