Although researchers have been focusing on sources, detectors have also
been improving. One example comes from Teledyne Dalsa, the Waterloo,
Ontario, Canada-based camera maker. In December 2010, the company
announced a CMOS line-scan camera with 1146-megapixel-per-second
throughput. The data rate is high enough that the camera requires a new
interface. Dubbed HSLink, it forms the foundation for Camera Link HS,
a proposed successor to the interface standard Camera Link.
Another example comes from Fairchild Imaging, a Milpitas, Calif.-based
company – currently being acquired by British defense contractor BAE Systems – that makes both CMOS- and CCD-based imaging systems. The company realized a few years ago, said Colin Earle, vice president of sales and
marketing for Fairchild Imaging, that the scientific community could use
a faster, higher sensitivity sensor with more dynamic range than CCDs
offer. The company therefore developed its scientific CMOS sensors.
Fairchild Imaging partnered with both Andor Technology plc of Belfast, UK,
and Kelheim, Germany-based PCO in bringing to market systems that are
based on the technology.
Earle said that the sensors and imaging systems based on them have been
well received. They offer capture rates of up to 100 fps, about five times
faster than comparable CCD sensors, but do so without sacrificing what’s
important to the target market.
In particular, researchers want a low-noise sensor, Earle said. “A scientist
cares about low noise because he wants to be able to measure faint signals,
and he’s got to ensure that his noise floor is below what he’s trying to
measure without resorting to multiplicative gain techniques that introduce
figured out how to produce light of nanometer wavelengths, which somewhat paradoxically will need mid-IR lasers operating
at 1.3 μm and longer, Murnane said.
With shorter wavelengths, the investigators will improve imaging resolution, since
the classical diffraction limit is about half
the wavelength. The push down from
extreme-ultraviolet, at 13 nm, into x-rays
as short as 1 nm should allow an equivalent
enhancement in resolving object details.
There’s another effect of this approach,
Kapteyn said. “If you do it under the right
conditions, you generate an attosecond
Like the wavelength, the pulse duration
is thousands of times smaller than the ori-
ginal. Results indicate that pulses of about
5 as can be generated. At 10− 18 seconds, an
attosecond is so short that light travels only
one-third of a nanometer. These brief bursts
of light should allow the capture of electron
dynamics in materials and molecules.
For imaging, the researchers illuminate
an object with a coherent beam and collect
the scattered light. Visually, this looks like
a mess, but it contains information from
which spatial data can be extracted.
What’s more, light below 4 nm is
absorbed by elements such as carbon
and nitrogen and so can provide elemental information. In particular, water is
relatively transparent in this region, but
carbon is strongly absorbing, leading to
an interesting possibility.
“You can image carbon content in an
x-ray image with 10-nm resolution for a
field of view that’s about the size of a
single cell,” Kapteyn said.
Nonbiological uses of the technique
could include tracking the dynamics of
semiconductors by following transistor heat
dissipation. For hard disks, changes in data
bit magnetization could be measured, an
important topic as the industry strives to
make higher-capacity disks.
Imaging is done by having the energetic
photons directly strike a CCD sensor,
which causes some chip damage. The technique is also limited to imaging depths of
only a few microns, and the beam itself has
to travel in vacuum. The sample being
imaged can sit in atmosphere, pressed up
against a transparent window.
The key to the latest advance has been a
better understanding of the nonlinear optics