Speaker
Description
Summary:
The project aims to modify a commercial scanning electron microscope with laser-based electron pulse generation and electron beam shaping to improve the microscope’s spatial resolution while enabling ultrafast, time-resolved electron microscopy.
Introduction:
To date, there is no product on the scanning electron microscope (SEM) market that can form and modify electron pulses using light emitted by a laser. This approach is suitable for the purpose of time-resolved "ultrafast" electron microscopy [1] and especially for the development of new methods for highly sensitive imaging, which is difficult to achieve using conventional approaches. Thanks to the possibility to manipulate the spatial phase profile of an electron beam with light [2], we are also able to obtain convex and concave electron lenses with focal lengths of several millimetres and also to create aberration correctors [3, 4]. The main idea of our project is to modify a commercial scanning electron microscope into a setup that would allow the creation of electron pulses, correction of electron beam aberrations, and external stimulation of the sample, all using a high-energy pulsed synchronous laser.
Setup diagram:
Our approach involves a high-power pulsed femtosecond laser, which will be introduced into the SEM at three distinct locations (1, 2, and 3), as illustrated in the simplified schematic in Figure 1. The purpose of optical branch 1 is to generate electron pulses, which then propagate through the microscope. Optical branch number 2 modulates the optical pulse, which then interacts with the electron pulse and changes it into the desired form. Finally, optical branch 3 is used to stimulate the sample, enabling the investigation of dynamic processes occurring within it.
Conclusions and results:
In our conference contribution, we will present details on the final target setup (sketched in Figure 1), with a particular focus on the optical branch 1 and the design of a source for ultra-short electron pulses generated by a pulsed laser, which is currently under experimental testing. We will describe the construction changes made to a commercial SEM allowing for the laser injection at the Schottky electron source. Next, we will explain the optical path used for precise laser focusing on the cathode tip. Finally, we will present the results of successful electron photoemission using a pulsed laser and the first experiments.
References:
[1] Feist A. et al.: Ultramicroscopy, Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam, 176 (2017).
[2] García de Abajo F.J. et al.: Physical Review Letters, Optical modulation of electron beams in free space, 126 (2021).
[3] Konečná A. et al.: Physical Review Letters, Electron beam aberration correction using optical near fields, 125 (2020).
[4] Chirita Mihaila M.C. et al.: Nature Photonics, Light-based electron aberration corrector, 19 (2025).
Acknowledgement:
We acknowledge the support of the Czech Science Foundation (GACR) under the Junior Star grant No. 23-05119M and the Brno Ph.D. Talent Scholarship funded by the Brno City Municipality.