| Contrary
to conventional wisdom, technology's advance into the
vanishingly small realm of molecules and atoms may not
be out of sight for the venerable optical microscope,
after all. In fact, research at the National Institute
of Standards and Technology (NIST) suggests that a hybrid
version of the optical microscope might be able to image
and measure features smaller than 10 nanometers--a tiny
fraction of the wavelength of visible light.
In a preliminary test of the
embryonic technique, NIST scientists used violet light
with a wavelength of 436 nanometers to image features
as small as 40 nanometers, about five times smaller
than possible with a conventional optical microscope.
Roughly speaking, such a feat
is akin to picking up a solitary dime with a clumsy
front-end loader. If successfully developed, the imaging
technology could be readily incorporated into chip-making
and other commercial-scale processes for making parts
and products with nanometer-scale dimensions.
The wavelengths of light in
the visible part of the spectrum greatly exceed nanoscale
dimensions. Consequently, the resolution of conventional
light-based imaging methods is limited to about 200
nanometers--too large to resolve the details of nanotechnology,
which, by definition, are no more than half that size.
However, a newly begun, five-year
research effort at NIST suggests that a novel combination
of illumination, detection and computing technologies
can circumvent this limitation. Success would extend
the technology's 400-year-long record as an indispensable
imaging and measurement tool well into the expanding
realm of nanotechnology.
Called phase-sensitive, scatter-field
optical imaging, the computer-intensive technique
under development at NIST uses a set of dynamically
engineered light waves optimized for particular properties
(such as angular orientation and polarization). How
this structured illumination field--engineered differently
to highlight the particular geometry of each type
of specimen--scatters after striking the target can
reveal the tiniest of details.
"The scattering patterns
are extremely sensitive to small changes in the shape
and size of the scattering feature," explains
Rick Silver, a physicist in NIST's Precision Engineering
Division.
Contact:
Mark Bello
mark.bello@nist.gov
301-975-3776
National Institute of Standards and Technology (NIST)
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