[3dem] astigmatism in low mag mode?

[Hagen, Wim J.]

Hi,

The diffraction lens is the focusing lens in LM mode, the diffraction stigmator then is the image stigmator. This stigmator is not shown in the system status. All stigmators have three channels (so three different settings to be ‘stored’), maybe some user dialled in extreme values in on of the channels.

Best,

Wim

From: 3dem <3dem-bounces at ncmir.ucsd.edu> On Behalf Of Morgan, David Gene
Sent: 19 April 2024 01:30
To: 3dem at ncmir.ucsd.edu
Subject: [3dem] astigmatism in low mag mode?

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Hi,

Has anyone else encountered terrible astigmatism in low mag mode on a TFS microscope?  We have run into this multiple times in the last several months on our Talos Arctica, and I am trying to understand what is causing it and how we can prevent it.

While looking at this problem, I also realized that I have no idea what lenses are changed when the focus in low mag mode is changed.  I grabbed several screen shots of the "system tab" in the TFS UI, looking for changes in the lenses and deflectors reported there.  Nothing seems to change, even though the images clearly change and the microscope reports defocus changes that seem to make sense...

Any thoughts would be appreciated.  Thanks in advance.
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