Phase contrast provides the best means to high resolution electron microscopy images. The phase shifts induced by the light atoms that make up biological specimens produce very little contrast, which is why we usually image out of focus. This takes advantage of phase shifts introduced by the CTF at the expense of more complicated image processing, and loss of information near CTF zeros.

Phase plates offer a potential solution, but have been hampered by difficulty in use (Zernike phase plate) and loss of signal due to additional inelastic scattering (Volta phase plate)

Scwartz et al. demonstrate the use of very intense (the most intense!) laser light to induce a selective phase shift enhancing image contrast in moderate energy (80 KeV) electrons.

The project web page can be found at:
http://matterwave.physics.berkeley.edu/phase-contrast-electron-microscopy

The paper discussed (Laser phase plate for electron microscopy) can be found: https://www.nature.com/articles/s41592-019-0552-2

A follow-up paper detailing the physics behind the laser:
https://arxiv.org/abs/1910.14441