Parameters needed¶

Need to enter:
Checkbox whether to do it at all or not.

Slit Width: Suggest to use 15 eV, since calibration was performed at that width. Generally we collect at 20 eV, but there is no problem to switch to 15 eV for the measurement

Exposure time: Default is 500 ms, which gives enough signal for the method to work. Can experiment with faster times if desired.

Mean free path: We measured mean free path to be 395 nm at NYSBC at 300 kV. It should depend only on the voltage.

Collect every N images: Since it adds overhead, you may want to do it only every 5 or 10 images.

Available in 3.4 version:¶

Objective Scattering Thickness estimate¶

Need to enter

Checkbox whether to calculate it or not
Exposure Counts over vacuum
Mean free path for objective scattering (also known as ALS coefficient: depends on instrument and aperture diameter.

• 300 is a good intitial guess if unknown
  Values determined at NYSBC:
• titan Krios 300 keV 20 eV slit, 100 um objective aperture: 322 nm
• titan Krios, 300 keV no EF, 100 um objective aperture: 3329 nm
• Tecnai F20 200 keV 100 um objective aperture: 392 nm
• Tecnai F20 200 keV 70 um objective aperture: 302 nm
• T12 120 keV 100 um objective aperture: 319 nm
• T12 120 keV 70 um objective aperture: 247 nm