Soft X-ray ptychography method at SSRF

Abstract

Ptychography is a diffraction-based X-ray microscopy technique in which an extended sample is scanned by a coherent beam with overlapped illuminated areas and complex transmission function of the sample is obtained by applying iterative phase retrieval algorithms to the diffraction patterns recorded at each scanned position. It permits quantitatively imaging of non-crystalline specimens at a resolution limited only by the X-ray wavelength and the maximal scattering angle detected. In this paper, the development of soft X-ray ptychography method at the BL08U1A beamline of Shanghai Synchrotron Radiation Facility is presented. The experimental setup, experimental parameters selection criteria, and post-experimental data analyzing procedures are presented in detail with a prospect of high-resolution image reconstruction in real time. The performance of this newly implemented method is demonstrated through the measurements of a resolution test pattern and two real samples: Pt–Co alloy nanoparticles and a breast cancer cell. The results indicate that strong scattering specimens can be reconstructed to sub-20 nm resolution, while a sub-25 nm resolution for biological specimens can be achieved.