Coherent diffraction microscopy at SPring-8: instrumentation, data acquisition and data analysis

Abstract

Since the first demonstration of coherent diffraction microscopy in 1999, this lensless imaging technique has been experimentally refined by continued developments. Here, instrumentation and experimental procedures for measuring oversampled diffraction patterns from non-crystalline specimens using an undulator beamline (BL29XUL) at SPring-8 are presented. In addition, detailed post-experimental data analysis is provided that yields high-quality image reconstructions. As the acquisition of high-quality diffraction patterns is at least as important as the phase-retrieval procedure to guarantee successful image reconstructions, this work will be of interest for those who want to apply this imaging technique to materials science and biological samples.

Method to enhance the resolution of x-ray coherent diffraction imaging for non-crystalline bio-samples

“…In addition, a × 21 21 pixel region at the centre is removed to emulate the beam stop which blocks the direct beam. Its size is not larger than the centro-speckle [8,29], as shown in figure 2(a). The reconstruction was performed with the guided hybrid input and output (GHIO) [30] method, an improvement of the HIO [31] method by adding the concept of optimization and guided search.…”

“…The theoretical analysis we made to reach equation (8) predicts that as the diffraction scattering intensity of the template becomes much larger than the sample, the noise contribution to the total signal will be proportional to β −1/2 , where β is defined in equation (9). This prediction has two parts.…”

“…The advancement in coherent diffraction imaging microscopy has enabled the determination of structures of non-crystalline materials in the nanometer scale [1][2][3][4]. By utilizing the iterative algorithm, the diffraction patterns captured by the CCD camera can be phased and thus a realspace structure can be reconstructed [5][6][7][8][9]. Because of its longer penetration depth than electrons, an x-ray is able to probe the structure below the surface of thick samples.…”

KOTOBUKI-1 apparatus for cryogenic coherent X-ray diffraction imaging

“…The frames work as guard corners to minimize parasite and background scattering coming from upper stream X-ray optics and enables us to collect diffraction patterns in very smallangle region necessary to retrieve reliable electron density map. 39,40 One pair is located at approximately 10-mm upstream of the sample position, and the other is at 200-mm (Figs. 2(b) and 2(c)).…”

“…The two L-shaped Si frames are organized to a two-dimensional block collimation optics together with the beam stop covering a quadrant of a PI-LCX1300 CCD detector (Princeton Instruments, USA), which is located at 2 or 3 m downstream from the specimen position. 9,13,39 The flux of X-ray beam was monitored by a PIN photodiode located at the downstream of the sample chamber, and was in the order of 10 8 photons/14 μmφ/s. CXDI experiments using XFEL are carried out at EH3 of BL3 in the SACLA facility 42 (Figs.…”