Top: the ALS beamline 9.0.1 experiment used a uniformly redundant array (URA) 30 nanometers thick with scattering elements 44 nanometers square (left). At right is the lithograph of Da Vinci’s Vitruvian Man. The scale bar is two micrometers long. Bottom: the FLASH experiment used a URA with 162 pinholes, next to a Spiroplasma bacterium. The 150-nanometer diameter pinholes in the URA limited resolution, but computer processing improved image resolution to 75 nanometers. The scale bar is four micrometers long.
The pinhole camera, a technique known since ancient times, has inspired a futuristic technology for lensless, three-dimensional imaging. Working at both the Advanced Light Source (ALS) at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, and at FLASH, the free-electron laser in Hamburg, Germany, an international group of scientists has produced two of the brightest, sharpest x-ray holograms of microscopic objects ever made, thousands of times more efficiently than previous x-ray-holographic methods.
The x-ray hologram made at ALS beamline 9.0.1 was of Leonardo da Vinci’s famous drawing, “Vitruvian Man,” a lithographic reproduction less than two micrometers (millionths of a meter, or microns) square, etched with an electron-beam nanowriter. The hologram required a five-second exposure and had a resolution of 50 nanometers (billionths of a meter).
The other hologram, made at FLASH, was of a single bacterium, Spiroplasma milliferum, made at 150-nanometer resolution and computer-refined to 75 nanometers, but requiring an exposure to the beam of just 15 femtoseconds (quadrillionths of a second).
The values for these two holograms are among the best ever reported for micron-sized objects. With already established technologies, resolutions obtained by these methods could be pushed to only a few nanometers, or, using computer refinement, even better.
The research paper at Nature Photonics
Massively parallel X-ray holography
Stefano Marchesini, Sébastien Boutet, Anne E. Sakdinawat, Michael J. Bogan1, Sas carona Bajt1, Anton Barty1, Henry N. Chapman1, Matthias Frank1, Stefan P. Hau-Riege1, Abraham Szöke1, Congwu Cui, David A. Shapiro, Malcolm R. Howells, John C. H. Spence, Joshua W. Shaevitz, Joanna Y. Lee, Janos Hajdu & Marvin M. Seibert
Advances in the development of free-electron lasers offer the realistic prospect of nanoscale imaging on the timescale of atomic motions. We identify X-ray Fourier-transform holography as a promising but, so far, inefficient scheme to do this. We show that a uniformly redundant array4 placed next to the sample, multiplies the efficiency of X-ray Fourier transform holography by more than three orders of magnitude, approaching that of a perfect lens, and provides holographic images with both amplitude- and phase-contrast information. The experiments reported here demonstrate this concept by imaging a nano-fabricated object at a synchrotron source, and a bacterial cell with a soft-X-ray free-electron laser, where illumination by a single 15-fs pulse was successfully used in producing the holographic image. As X-ray lasers move to shorter wavelengths we expect to obtain higher spatial resolution ultrafast movies of transient states of matter.