# Dichography: Two-frame Ultrafast Imaging from a Single Diffraction Pattern

## TL;DR

Dichography is a novel method that separates overlapping diffraction signals from two time-delayed ultrafast X-ray pulses, enabling ultrafast imaging of nanostructures with high spatial resolution.

## Contribution

The paper introduces Dichography, an algorithmic approach to independently reconstruct two images from overlapping diffraction patterns in ultrafast X-ray imaging.

## Key findings

- Successfully reconstructed two views of nanodroplets with 20 nm resolution
- Validated method with silver nanoparticle pairs
- Observed structural stability at delays up to 750 fs

## Abstract

We experimentally demonstrate that pairs of time-delayed ultrabright and ultrashort X-ray pulses of two different colors, delivered by modern X-ray Free Electron Lasers, can provide two time-delayed snapshots of a sample. We introduce Dichography, a method that algorithmically separates the diffraction signals overlapping on the detector and independently retrieves the two images of the specimen. We employ Dichography to reconstruct two views of individual xenon-doped helium nanodroplets with 20 nm spatial resolution. The consistency of structures observed in both images at delays up to 750 fs provides evidence that, under these illumination conditions, significant structural damage only occurs at longer timescales. We further validate the method by imaging pairs of silver nanoparticles intercepted by the same light pulse. Dichography enables a new class of experiments across physics, chemistry, and materials science, making a significant step toward the original promise of X-ray free-electron lasers to capture ultrafast movies of nanomatter.