The Scatman: an approximate method for fast wide-angle scattering simulations

TL;DR

The paper introduces the Scatman, a fast approximate computational method for simulating wide-angle scattering patterns in coherent diffraction imaging, enabling efficient 3D structural analysis of nanoscale objects from single diffraction images.

Contribution

It presents the Scatman algorithm and its open-source implementation PyScatman, which significantly speeds up wide-angle scattering simulations for 3D imaging applications.

Findings

PyScatman computes scattering patterns in milliseconds.

The method provides quantitative results for weakly scattering samples.

Enables systematic 3D imaging from single diffraction patterns.

Abstract

Single-shot Coherent Diffraction Imaging (CDI) is a powerful approach to characterize the structure and dynamics of isolated nanoscale objects such as single viruses, aerosols, nanocrystals or droplets. Using X-ray wavelengths, the diffraction images in CDI experiments usually cover only small scattering angles of few degrees. These small-angle patterns represent the magnitude of the Fourier transform of the two-dimensional projection of the sample's electron density, which can be reconstructed efficiently but lacks any depth information. In cases where the diffracted signal can be measured up to scattering angles exceeding 10 degrees, i.e. in the wide-angle regime, three-dimensional morphological information of the target is contained in a single-shot diffraction pattern. However, the extraction of the 3D structural information is no longer straightforward and defines the key challenge in wide-angle CDI. So far, the most convenient approach relies on iterative forward fitting of the scattering pattern using scattering simulations. Here we present the Scatman, an approximate and fast numerical tool for the simulation and iterative fitting of wide-angle scattering images of isolated samples. Furthermore, we publish and describe in detail our Open Source software implementation of the Scatman algorithm, PyScatman. The Scatman approach yields quantitative results for weakly scattering samples. PyScatman is capable of computing wide-angle scattering patterns in few milliseconds even on consumer-level computing hardware. The high computational efficiency of PyScatman enables effective data analysis based on model fitting, thus representing an important step towards a systematic application of 3D Coherent Diffraction Imaging from single wide-angle diffraction patterns in various scientific communities.