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SCIENTISTS CREATE HIGH RESOLUTION ELECTRON MICROSCOPE
For the past 50 years, electron optics engineers have sought
to improve the precision of electron microscopes by counteracting
the image-blurring effects of lens imperfections, or "aberrations."
The largest imperfection, "spherical aberration,"
cannot be fixed in a single lens.
To address this problem, IBM (Yorktown Heights, NY) and Nion
(Kirkland, WA) scientists combined seven new sets of magnetic
lenses with modern computers to actively correct the aberration
in real-time.
After the correction, the microscope can make an electron
beam that is only 75 thousandths of a nanometer (3 billionths
of an inch) -- smaller than a single hydrogen atom. This is
the smallest electron beam produced in an electron microscope
to date.
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the complete story.
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TECHNOLOGY OF THE MONTH: LINEARIZATION CIRCUIT DEVICE
This linearization circuit device is for an electro-optical
modulator where an electrical modulation signal is divided
by an anti-phase dividing element and is distorted by two
distortion elements. The electro-optical modulator has two
differential inputs, which receive the individual signals.
The linearization circuit device of this invention eliminates
the need for at least one of the 180-degree hybrids (anti-phase
dividing element). Since 180-degree hybrids contain broadband
HF transformers, which produce amplitude and phase-response
errors, their influence in the signal path between the linearization
circuit device and the electro-optical modulator is especially
high. Therefore, eliminating a 180-degree hybrid improves
the amplitude and phase response and the attainable linearity
for the electro-optical modulator.
Moreover, the necessary amplification of the pre-distorted
individual signals is reduced, so that the appropriate amplifier
delivers a smaller intermodulation contribution to the individual
signals.
Finally, driving the electro-optical modulator in push-pull
operation eliminates an unwanted phase modulation of the optical
output signal (chirp), which improves the optical signal quality,
especially for long transmission distances.
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QUANTUM DOT ISOLATION, MILESTONE FOR OPTICAL ENGINEERING
Scientists from the National Institute of Standards and Technology
(NIST)
Optoelectronics Division have characterized the optical emission
from a single, isolated "quantum dot."
Quantum dots are electronic nanostructures that spatially
confine electrons and restrict these electrons to a single
state, similar to an individual atom. By isolating a single
quantum dot and studying its optical emission, scientists
can begin designing a single photon turnstile, a device for
generating single photons on demand
That technology eventually could lead to quantum-based radiometry
standards and highly advanced cryptography systems. Better
understanding of the charge carrier processes in quantum dots
will also help produce the next generation of optical devices
such as laser diodes, photodetectors and optical amplifiers.
View this story
or for or more technical information on this development,
contact Richard Mirin at mirin@boulder.nist.gov.
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INDUSTRY UPDATE
YKK
Corporation of America (YCA, Marietta, GA) has launched
its new North American Optical Components Division, also located
in Marietta, GA.
Ocean Optics (Dunedin,
FL) has formed an Applications Group. This team of Ph.D-level
scientists and engineers will provide R&D services and
technical support, including opto-electronic design and integration
services, prototype development, and testing and validation
for most optical-sensing applications.
Indigo Systems
(Goleta, CA) has moved their corporate headquarters to 50
Castilian Dr., Goleta, CA 93117-3027. This is the company's
third major expansion in the past five years.
Stratos Lightwave
(Chicago, IL) has joined the 10-Gigabit Small Form-factor
Pluggable (XFP) Module Group, a module Multi Source Agreement
(MSA) association. The purpose of the group is to develop
a vendor-independent specification for ultra-small form factor
10 Gb/s communication modules.
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