Design for light-based spherical aberration correction of ultrafast electron microscopes

TL;DR

This paper proposes a theoretical method using ponderomotive interactions and optimized light shaping to correct spherical aberrations in ultrafast electron microscopes, enhancing image quality.

Contribution

It introduces a novel approach combining light-based interactions and algorithmic optimization for aberration correction in electron microscopy.

Findings

Aberration correction achieved with an angle of 8.1 mrad.

Use of gradient descent to optimize light beam shaping.

Simulation results show effective spherical aberration compensation.

Abstract

We theoretically demonstrate that ponderomotive interactions near the electron cross-over can be used for aberration correction in ultrafast electron microscopes. Highly magnified electron shadow images from Si$_3$N$_4$ thin films are utilized to visualize the distortions induced by spherical aberrations. Our simulations of electron-light interactions indicate that spherical aberrations can be compensated resulting in an aberration free angle of \SI{8.1}{mrad}. For achieving the necessary light distribution, we use a gradient descent algorithm to optimize Zernike polynomials and shape the light beam into a modified Gaussian and Laguerre-Gaussian beam.