Improving Autofocusing¶

Because MSI-raster is normally used for acquiring images on negatively stained particles on continuous carbon, the intermediate mag preset (hl) often lacks contrast. To reduce focusing failure, we recommend a different focusing sequence for the Z focus node.

• Use Stage Alpha Tilt to determine defocus at the low magnification sq preset to do a rough stage-z adjustment to U-center

• Refine stage-z position at the high magnification fa preset and Use beam-tilt to determine the required correction.

For "Stage_Wobble" Step:

• Enable = Yes

• Image registration= phase correlation

• Fit limit = 1000 (not used)

• Correct for delta Defocus/Z between 0 and 2e-4 meters

• Correction type = Stage Z

• Check drift greater than 3e-10 meters/s = No

• Stigmator correction = No

• Stigmator Defocus Max/Min = N/A

For "Z_to_Eucentric" Step, change these:

• preset = fa

• Correct for delta Defocus/Z between 0 and 2e-5 meters