Compressed Ultrafast Electron Diffraction Imaging Through Electronic Encoding

Ultrafast electron diffraction (UED) with high temporal and spatial resolutions is a powerful tool to observe transient structural changes in materials on an atomic scale. This technique is based on a pump-probe method using ultrashort laser and electron pulses. Therefore, UED requires that the measured transients be highly repeatable. Moreover, the relative time jitter between laser and electron pulses significantly affects the UED temporal resolution. To overcome the UED technical limitations, we propose a technique called compressed ultrafast electron diffraction imaging (CUEDI). In this technique, we encode time-evolving electron diffraction patterns with random codes on an electron encoder. Then, the encoded electron diffraction pattern is measured by a detector after a temporal shearing operation. Finally, the evolution process of the electron diffraction pattern is reconstructed using a compressed sensing algorithm. We confirm the feasibility of our proposed scheme by numerically simulating the polycrystalline gold melting process based on the experimental data measured with the pump-probe method. Because CUEDI employs a continuous or long electron pulse, the relative time jitter between laser and electron pulses can be eliminated. Additionally, CUEDI measures transients with a single shot, which allows irreversible processes to be directly observed.