High-Power Near-Concentric Fabry-Perot Cavity for Phase Contrast Electron Microscopy

TL;DR

This paper advances laser-based phase plates for cryo-electron microscopy, achieving record intensities and demonstrating stable operation during standard cryo-EM data collection to enhance biological sample imaging.

Contribution

It reports improved high-power laser cavities capable of producing optimal phase shifts and demonstrates the first cryo-EM reconstruction using a laser phase plate.

Findings

Achieved record continuous-wave intensities over 450 GW/cm².

Demonstrated stable laser phase plate operation during cryo-EM data collection.

First cryo-EM reconstruction using a laser phase plate.

Abstract

Transmission electron microscopy (TEM) of vitrified biological macromolecules (cryo-EM) is limited by the weak phase contrast signal that is available from such samples. Using a phase plate would thus substantially improve the signal-to-noise ratio. We have previously demonstrated the use of a high-power Fabry-Perot cavity as a phase plate for TEM. We now report improvements to our laser cavity that allow us to achieve record continuous-wave intensities of over 450 GW/cm$^{2}$, sufficient to produce the optimal 90{\deg} phase shift for 300 keV electrons. In addition, we have performed the first cryo-EM reconstruction using a laser phase plate, demonstrating that the stability of this laser phase plate is sufficient for use during standard cryo-EM data collection.