# Exact Crystalline Structure Recovery in X-ray Crystallography from Coded Diffraction Patterns

## TL;DR

This paper introduces a coded aperture system in X-ray crystallography that guarantees exact structure recovery with fewer measurements, reducing exposure time and preserving crystal integrity.

## Contribution

It presents a novel coded diffraction pattern approach with proven exact reconstruction guarantees and an efficient algorithm leveraging sparsity in Fourier domain.

## Key findings

- Exact reconstruction guarantees up to a global phase shift.
- Requires 50% fewer measurements than existing methods.
- Reduces crystal exposure time, minimizing damage.

## Abstract

X-ray crystallography (XC) is an experimental technique used to determine three-dimensional crystalline structures. The acquired data in XC, called diffraction patterns, is the Fourier magnitudes of the unknown crystalline structure. To estimate the crystalline structure from its diffraction patterns, we propose to modify the traditional system by including an optical element called coded aperture which modulates the diffracted field to acquire coded diffraction patterns (CDP). For the proposed coded system, in contrast with the traditional, we derive exact reconstruction guarantees for the crystalline structure from CDP (up to a global shift phase). Additionally, exploiting the fact that the crystalline structure can be sparsely represented in the Fourier domain, we develop an algorithm to estimate the crystal structure from CDP. We show that this method requires 50% fewer measurements to estimate the crystal structure in comparison with its competitive alternatives. Specifically, the proposed method is able to reduce the exposition time of the crystal, implying that under the proposed setup, its structural integrity is less affected in comparison with the traditional. We discuss further implementation of imaging devices that exploits this theoretical coded system.