Image/Beam Alignment in Tecnai UI
Added by Matthias Brunner about 14 years ago
Hi there!
Leginon is running rather smoothly, collecting lots of data :)
Two issues came up, though:
The image/beam alignment seems to be a bit off recently, so image shift is causing some beam shift.
And second, also recently, when I am acquiring with non-zero image-shift, changing defocus causes additional image shift.
Does anyone of you know which alignments exactly (their name in the FEI Tecnai UI) will most likely correct those two problems? On a Polara, btw.
Cheers
Matthias Brunner
Replies (1)
RE: Image/Beam Alignment in Tecnai UI - Added by Anchi Cheng about 14 years ago
Hi, Matthias,
Answer 1: Alignments/Image HM-TEM/Image/Beam calibration on Tecnai F20
Answer 2: This is natural. Without it, Beam-Tilt based auto-focus would not have worked. If you need to keep that image-shift as your preset, such as in the case of tomography or RCT where you know your goniometer tilt axis is off significantly from the CCD center, you may do your rotation center alignment at that particular preset image shift. Of course you can't use Tecnai User Interface for it because it will automatically put image shift to zero when it starts, you will have to do it in Leginon. First make a very good Defocus calibration with zero image shift and rotation center for that, and then send the preset image shift to the scope. You can then use the tool that align rotation center to do the alignment. The alignment is an inverse of the equation used to calibrate the defocus, which is why the first step is important.