Imaging the phase plate slot to check for contamination and recovery of the irradiated spots¶

Phase plates conditions are not always consistent. It is useful to monitor its global state once a month if used often to look for new contaminant and the recovery of irradiated spots. Here is the condition we use at NRAMM/SEMC.

1. Go to low enough magnification that most of the Volta phase plate slot is visible on the camera that will be used to capture the image. We use 64x on Krios and take this image on Ceta camera.

2. Spread the beam to cover the camera and adjust spot size if needed and defocus to -100 mm if possible. This allows good contrast to observe the phase plate.
3. Advance the phase plate patches or use aperture adjustment function to center the slot.
4. Take an image.