Hard X-ray Fourier transform holography from an array of oriented referenced objects.

Hard X-ray Fourier transform holography (HXFTH) is a promising method for imaging nanoscale objects, including biological molecules, with a spatial resolution of a nanometer or better. However, it suffers from low scattering intensities being available for imaging owing to smaller object size and the low scattering cross section inherent in hard X-rays. One technique to overcome the problem would be to use an array of oriented objects, each with its own reference. Here the feasibility of this approach was experimentally tested by recording diffraction patterns from nanofabricated test patterns arranged in a 5 × 5 matrix. At an X-ray energy of 8 keV (λ = 1.55 Å), the image of the original test pattern was clearly restored with 60 s exposure on an imaging plate; the image was still recognizable with a 500 ms exposure on a CCD detector at the BL40XU beamline at SPring-8. The results demonstrate that the use of an array of referenced oriented objects for HXFTH is workable, and that it can be considered as a practical candidate for imaging biological molecules, identical particles of which are available but diffract even more weakly than artificially fabricated test patterns.