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Massively Parallel X-Ray Holography

Posted by Soulskill on from the thank-you-for-not-inventing-a-witty-acronym dept.

Roland Piquepaille writes "An international group of scientists has produced some of the sharpest x-ray holograms of microscopic objects ever made. According to one of them, they improved the efficiency of holography by a factor of 2,500. In order to achieve these spectacular results, they put a uniformly redundant array next to the object to image. And they found that this parallel approach multiplied 'the efficiency of X-ray Fourier transform holography by more than three orders of magnitude, approaching that of a perfect lens.' Besides these impressive achievements, it's worth noting that this technology has been inspired by the pinhole camera, a technique used by ancient Greeks. 'By knowing the precise layout of a pinhole array, including the different sizes of the different pinholes, a computer can recover a bright, high-resolution image numerically.'"

6 of 41 comments (clear)

  1. "Computer processing improved the resolution" ? by gardyloo · · Score: 4, Interesting

    I'm a bit skeptical. Whatever information one can get is present in the original diffraction pattern. "Processing" *probably* means interpolation, or convolution with the known regular array. One can only keep the same information already present, or lose information in this way. They probably mean that the pattern was smoothed so as to look nicer to the eye (which is certainly valid), but I doubt they increased resolution in any way.

    1. Re:"Computer processing improved the resolution" ? by FilipeMaia · · Score: 5, Interesting

      By post processing they mean the phasing algorithm. The imaging method is divided in two parts. First they recover a low resolution image of the object that was imaged by looking directly at the hologram and deconvoluting with the known pinholes (in this case a Uniformly redundant array (URA), which assures that the deconvolution is well behaved). This step cannot achieve a resolution higher than the size of the pinholes in the URA. In a second step the entire image is phased, meaning that an algorithm is aplied to it that tries to mimick a lense. This increases the resolution obtained to the maximum possible, that is to the limit of the numerical aperture.

    2. Re:"Computer processing improved the resolution" ? by gardyloo · · Score: 2, Interesting

      Interestingly enough, if one captures all of the phase data (as by using not-quite-evanescent waves), the resolution isn't restricted by the classical far-field limit of 1/2 wavelength. Because they're doing holography, they should be capturing at least *some* of the phase info.

  2. Appeal Denied by RickRussellTX · · Score: 1, Interesting

    From TFA:

    The hologram of the Spiroplasma bacterium was made in precisely the same way, with much brighter x-ray beams and a much shorter pulse of light. So bright was the flash of light that the sample was vaporized...

    The prisoner's last meal consisted of an enriched sugar/protein broth. He elected not to speak to a priest. His last words were, "It is a far, far better thing that I do, than I have ever done before."

  3. "2500 times more efficient" can mean... by jeffb+(2.718) · · Score: 3, Interesting

    2500 times better signal/noise, or (I think) 50 times better resolution, or 2500 times shorter exposures, or 2500 times less radiation intensity.

    Conventional X-ray and CT imaging are vastly different from X-ray holography, but this research might well end up contributing to those modalities as well. Everyone would be very happy to get useful resolution with vastly lowered exposures.

  4. arrays of pinholes, huh? by ErkDemon · · Score: 2, Interesting

    Time to reinvent the Nipkow disk?

    --
    Eric Baird