Experimental lensless soft-X-ray imaging using iterative algorithms: phasing diffuse scattering

Acta Cryst. (2003). A59, 143–152

Clusters of gold balls, 50 nm diameter, imaged using soft x-rays. Image obtained using iterative algorithm to solve the phase problem. Resolution about 10 nm.

Phase information is encoded in diffuse x-ray scattering from nonperiodic objects if it is sampled finely enough. The Fienup HiO iterative algorithm has proven the most successful method of extracting it. We record soft x-ray (λ = 2.1 nm) transmission speckle patterns from clusters of 50 nm diameter gold balls lying on a transparent substrate. We use the HiO algorithm to solve the phase problem and so reconstruct images of the balls. The presence of an isolated ball also produces a faithful image in the Patterson map. A reconstructed image is shown to the right. Beam stops, absorption filters, density modification and Fourier transform holography are also discussed.