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Before Russell Kerschmann came along, the world through a
microscope looked much the way people perceived the world
at large to be before Columbus set sail: flat. Microscopes
let us see an object's surface and get some sense of its insides,
but its true three-dimensional architecture remained a mystery.
No one knew exactly how the two parts of Velcro attach, or
precisely how the network of pores in a paper towel enable
it to suck up water, or even how the three different layers
that make up our skin interact. Then Kerschmann invented a
new kind of microscope -- and it's revolutionizing the way
scientists see.
Scientists at Procter and Gamble, for example, are harnessing
Kerschmann's technology to study how bone reacts to various
drugs as it grows. Engineers at Sandia National Laboratories
are employing the new scope to measure the tiny screws and
gears they use to build microscopic robots. "We'd be up a
creek without it," says Christine Miller, a pediatric cardiologist
at the University of Rochester. Miller is using the new imaging
technique to investigate whether raising blood pressure around
embryonic chick hearts can cause congenital heart defects.
"We've gone through a year and half of doing this with other
technology and have gotten nothing." What began as a device
that took up too much room on Kerschmann's kitchen table is
now the hub of a multimillion-dollar company, Resolution Sciences
Corp., based in Corte Madera, California. The technology,
called digital volumetric imaging, provides scientists with
accurate three-dimensional images of almost anything they
care to look at up close. The images can be rotated and viewed
from any angle; they can also be opened up to reveal the sample's
interior.
Kerschmann's images are so different from what came before
that they are even teaching manufacturers and scientists things
they never knew about their own products. When Kerschmann
imaged Velcro, for example, he learned that the material is
inefficiently constructed -- most of the binding fibers never
make contact.
Kerschmann's images could help manufacturers engineer a form
of Velcro that's just as strong but costs less to make. "In
our lab, I see things almost every day that no one's ever
seen before," Kerschmann says. "And we're just beginning to
learn all the applications of the technology."
People have been peering into microscopes for more than 150
years to get a close-up look at the natural world, and the
devices have become increasingly sophisticated. But existing
microscopes run into problems when magnifying samples that
are larger than a few hairs' diameter. They cannot capture
the samples' internal details three-dimensionally.
A medical pathologist, Kerschmann encountered this problem
firsthand about 15 years ago, when he was working at the Wellman
Laboratories of Photomedicine at Massachusetts General Hospital
in Boston. The lab was developing a laser treatment for the
inflated blood vessels that cause unsightly skin imperfections
such as port wine stains and spider veins. Kerschmann's task
was to determine the specific laser energy and pulse length
that would collapse the blood vessels without damaging collagen,
the protein that gives skin its elasticity.
Doctors would take skin samples from volunteers, then Kerschmann
would embed them in wax and slice them into paper-thin sections.
He then examined each section under a microscope to see where
in the branching network of blood vessels the laser hit first.
But Kerschmann was soon frustrated. The 2-D world he was seeing
through existing scopes could not help him answer what was
essentially a 3-D problem.
"I couldn't get a good look at them," he recounts. "You see
the round cross sections through each of the the vessels,
but they don't tell you much about how the vessels interconnect
and branch."
It was possible, Kerschmann knew, to generate a composite
3-D computer image that would reflect all the individual sections
of his sample. But he also knew that the cutting process so
distorts and damages the slices that piecing them back together
afterward would create a grossly inaccurate picture. It would
be like slicing up a soft loaf of bread, then gluing the squashed
slices back together and assuming you'd reconstructed the
shape of the original loaf.
Kerschmann eventually figured out a way to get around the
cutting problem. Instead of dicing up an object at the outset
and placing it on hundreds of glass slides -- the traditional
method -- he decided to alternate imaging and cutting the
object in a sequential process that is ultimately more precise.
Kerschmann usually begins his process with a sample about
the size of a pencil eraser. It is stained with fluorescent
dyes and embedded in hard black plastic. He then clamps it
to his microscope. The scope shoots laser light through the
sample, which excites the fluorescent dyes. A digital camera
captures the image, and then a blade slices off the sample's
outer layer. That layer, which has been damaged by the cutting,
is discarded; the rest of the sample, however, remains intact.
Next, the sample's freshly exposed layer is imaged; then it
too is removed. As this two-part process is repeated over
and over, the sample slowly shrinks until there is nothing
left of it. What is left, however, are the 1,000 or so images
of each of its layers, stored on a computer. A software program
compiles them into a single, luxuriously detailed, three-dimensional
view of the original sample.
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