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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Dear David,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">The column alignments are exactly what the name suggest, this is to align the column. In principle this is everything below the first cross-over of the FEG. The column alignments are
very stable and in principle do not change. Especially for cryo-EM you should only have one column alignment file per high tension and this is mostly the highest HT you have on your microscope. There is very little reason to use a Krios at any other KV than
300 and a glacios at 200kV since the DED still have the highest DQE at higher HT. When the 100kV detectors come out this might be different, but for now the default is basically the highest kV of your system is optimal.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">In principle the only thing that really changes over time is the FEG. Hence the first step of the column alignment which is the FEG can be separately store in the FEG register. You in
general first load a column alignment and then load the most recent FEG register.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">For MS applications it is often the case that different FEG settings might be used. For instance you might want to change the gun lens. In that case you need a slightly different FEG
alignment for that GL and thus have a second FEG register. Since a different FEG setting also is often related to a different mode the FEG register has the option to also save the mode, stigmator settings and a few other options you can see in the flap out.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">What users however started doing is to sometimes go as far as saving feg registers for a change in stigmator settings. OR any mode change also re-align the column. TFS engineers also
sometimes have the “routine” of re-alignming the column over and over again with any change that is made. You then run the risk of getting wildgrow in alignment files and FEG registers.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">So the way it I supposed to be: 1 alignment file for 1 HT. 1 FEG register for the most recent gun settings. IF you do not need to change your gun for different applications you do not
need more that 1 FEG register! In cryo applications with a counting detector that only allows a relatively narrow dose rate for optimal performance this is normally only 1 GL setting and thus only 1 FEG register. A simple as possible! If you FEG changes over
time, you run through ONLY the gun alignment ones and UPDATE the FEG register. <o:p>
</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Any stigmmation, coma and direct tunings should be taken care of by the autofucntions, quickly before each new run.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Hope this helps<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Cheers
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Matthijn
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> 3dem <3dem-bounces@ncmir.ucsd.edu>
<b>On Behalf Of </b>Morgan, David Gene<br>
<b>Sent:</b> Thursday, May 4, 2023 10:22 PM<br>
<b>To:</b> 3dem@ncmir.ucsd.edu<br>
<b>Subject:</b> [3dem] best practice question for ThermoFisher microscopes<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Hi,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">I recently realized that different TFS service engineers have told us different things about best practices for using the FEG registers and alignment files on our Talos
Arctica. One of the engineers told us to use the FEG registers to store the current best FEG settings and to use a series of alignment files to store things like commonly used imaging conditions for different tasks. Another engineer said to use FEG registers
for both purposes.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Is there a general consensus on this, and if not, what do people think are the advantages of using one over the other?<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">Thanks in advance for any responses.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal"> politics is more difficult than physics.<o:p></o:p></p>
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<p class="MsoNormal"> A. Einstein<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> David Gene Morgan<br>
Electron Microscopy Center<br>
047E Simon Hall<br>
IU Bloomington<br>
812 856 1457 (office)<br>
812 856 3221 (3200)<br>
<a href="https://urldefense.com/v3/__http:/iubemcenter.indiana.edu__;!!Mih3wA!DJ5tp3ZubyXQZZYMhoRChKoq89H4-BlS-xGpFSf1QuysMZmx5YhUVDV7DjAD9s38tYfDfB65ZZExZxkesaFHNoI$">
http://iubemcenter.indiana.edu</a><o:p></o:p></p>
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