High-power near-concentric Fabry-Perot cavity for phase contrast electron microscopy

Area of Science:

• Physics
• Microscopy
• Structural Biology

Background:

• Transmission electron microscopy (TEM) of vitrified biological macromolecules, known as cryo-electron microscopy (cryo-EM), suffers from weak phase contrast, limiting image quality.
• Phase plates are crucial for enhancing contrast in cryo-EM by manipulating the phase of electron waves.
• Previous work established a high-power Fabry-Perot cavity as a potential phase plate for TEM.

Purpose of the Study:

• To report improvements to a laser cavity phase plate for TEM.
• To demonstrate the capability of the improved phase plate for cryo-EM reconstructions.
• To assess the stability of the laser phase plate for routine cryo-EM data collection.

Main Methods:

• Development and optimization of a high-power Fabry-Perot laser cavity.
• Characterization of continuous wave intensities achieved by the laser cavity.
• Performance of cryo-electron microscopy (cryo-EM) reconstruction using the laser phase plate.

Main Results:

• Achieved record continuous wave intensities exceeding 450 GW/cm².
• Demonstrated the ability to produce an optimal 90° phase shift for 300 keV electrons.
• Successfully performed the first cryo-EM reconstruction utilizing the laser phase plate.

Conclusions:

• The improved laser phase plate offers significantly enhanced performance for cryo-EM.
• The demonstrated stability is sufficient for standard cryo-EM data acquisition.
• This technology promises to improve signal-to-noise ratios and image quality in cryo-EM.