Lensless camera for nanoscale imaging
Australian and U.S. scientists have developed a lensless camera which uses X-rays to view nanoscale materials and biological specimens. As says one researcher, 'there is no lens involved at all; instead, a computer uses sophisticated algorithms to reconstruct the image.' Future microscopes equipped with these lensless cameras could be used in a variety of biology and biomedicine applications. They also be used in nanoengineering to develop more efficient catalysts for the petrochemical and energy industries. But read more...
You can see on the left a "schematic layout of the resonant x-ray diffraction microscope. Two diffraction patterns are acquired below and above the absorption edge of a specific element and are directly phased to obtain high-resolution images. The difference of the two images represents the spatial distribution of the specific element. The ultimate resolution of the microscope is limited only by the x-ray wavelengths and can in principle reach the atomic level." (Credit: The research team)
The lensless camera was developed in the Advanced Photon Source (APS) at Argonne National Laboratory. APS is a national synchrotron X-ray research facility funded by the U.S. Department of Energy. The lead researcher at APS is Ian McNulty, who thinks that "this technique will enhance our understanding of many problems in materials and biological research" and that it can "be extended beyond the current resolution of about 20 nanometers to image the internal structure of micrometer-sized samples at finer resolution, reaching deep into the nanometer scale."
For this project, Argonne scientists collaborated with other researchers from the University of California at Los Angeles, the University of Melbourne, Australia, La Trobe University, also in Melbourne, and the Australian Synchrotron facility.
You can see on the left how "Argonne scientists and collaborators used high energy X-rays from the Advanced Photon Source to create detailed images of nanoscale materials. The scientists are working to develop a dedicated facility for the process at Argonne. (Credit: Argonne National Laboratory) Here is a link to a larger version of this photo.
So what's behind this lensless camera? "The key is the high intensity X-ray beams created at the APS at Argonne. An intense, coherent X-ray beam collides with the sample, creating a diffraction pattern which is recorded by a charge coupled device (CCD) camera. The X-ray energy is tuned to an atomic resonance of a target element in the sample. Using sophisticated phase-recovery algorithms, a computer reconstructs an image of the specimen that highlights the presence of the element. The result is an image of the internal architecture of the sample at nanometer resolution and without destructive slicing."
For more information, this research work has recently been published in the journal Physical Review Letters under the title "Nanoscale Imaging of Buried Structures with Elemental Specificity Using Resonant X-Ray Diffraction Microscopy" (Volume 100, Number 2, Article 025504, January 18, 2008).
Here is a short excerpt of the abstract. "We report the first demonstration of resonant x-ray diffraction microscopy for element specific imaging of buried structures with a pixel resolution of ~15 nm by exploiting the abrupt change in the scattering cross section near electronic resonances. [...] We anticipate that resonant x-ray diffraction microscopy will be applied to element and chemical state specific imaging of a broad range of systems including magnetic materials, semiconductors, organic materials, biominerals, and biological specimens."
Finally, here is a link to the full paper (PDF format, 4 pages, 1.54 MB), from which the top image of this post has been extracted.
Sources: Argonne National Laboratory news release, February 19, 2008; and various websites
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