<div dir="auto"><div><br></div><div>Dear Piotr,</div><div dir="auto"><br></div><div dir="auto">Beam drift might have two main causes: </div><div dir="auto"><br></div><div dir="auto"><b>1- Tempetature: </b>The most plausible cause is changing the temperature, either ambient, lens or water temperature. The most sensitive parts there are C2 and Obj. The temperature induced drift is gradual and steady.</div><div dir="auto"><b><br></b></div><div dir="auto"><b>2- Hysteresis: </b>The second plausible reason might be hysteresis of C2. It is more problematic in most of the older JEOL microscopes where you could not change the C2 current abruptly (e.g wobbling for aperture centering etc.). Glacios also has some considerable hysteresis in its C2 but it does not end in beam cut offs if you use a proper (big enough) C2 aperture or in general if you use the microscope in the recommended optical set ups.</div><div dir="auto"><br></div><div dir="auto">For characterizing the true cause of the drift, please change one parameter at the time. For that reason please go to diffraction and image mode using hand panel not EPU-D software. EPU-D does some extra steps and corrections which might be misleading. You can then characterize the responsible parameter. Monitor the water and ambient temperature using extra sensors and data loggers. I did it myself. You wont believe how much insight you might get. You can also read the lens temperature using the engineer's monitoring software. Ask this from your engineer to give you access to the microscop's parameters graphs. Change the current of each lens separately. Doing all these steps you can analyze the situation. Also make sure if the normalization functions are set up correctly.</div><div dir="auto"><br></div><div dir="auto">I guess according to what you described it is a thermal issue which leads to a steady beam drift. Specially if it happens in one direction e.g. x or y or in between. So monitoring lens temperatures are the first thing to go.</div><div dir="auto"><br></div><div dir="auto">And at the end you should not expect the ultimate stability like a Krios. As mentioned before it has a decent amout of C2 hysteresis. Moreover the lenses (except the objective) are not constant powers. You should deal with a bit of instabilities.</div><div dir="auto"><br></div><div dir="auto">Cheers</div><div dir="auto"><br></div><div dir="auto">Ferrie- Halle</div><div dir="auto"><br></div><div data-smartmail="gmail_signature">Dr.-Ing Farzad Hamdi, <br>EM Engineer - Staff Scientist<br>Kastritis Laboratory for Biomolecular Research (KLBR)<br>Cryo-Electron Microscopy & Computational Structural Biology<br>__<br>Institute of Biochemistry and Biotechnology<br>Martin-Luther-Universität Halle-Wittenberg (MLU)<br>ZIK HALOmem & Biozentrum, Room A.2.14 & 15<br>Weinbergweg 22, 06120, Halle (Saale), Germany<br><br><br>Phone: <br><br><br>Office: +49 345 5524984<br>Glacios Room: +49 345 5524883<br>JEM-3200FSC Room: +49 345 5524868 <br><br>web (Lab): <a href="https://urldefense.com/v3/__https://blogs.urz.uni-halle.de/kastritislab/__;!!Mih3wA!GPZ7X_AhVEo7QtYIaOstPub1aVYf4pn9b52bTArE2p9UGKvDCDWVoqPmtfelqNXxEDyT7gokXVWTxjk-Rg$">https://blogs.urz.uni-halle.de/kastritislab/</a><br><br>Achtung: Falls Sie diese E-Mail auf Deutsch erhalten, bedenken Sie bitte, dass sie mit dem Deepl AI Übersetzer übersetzt werden könnte.<br> </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Feb 13, 2024, 10:52 Piotr Szwedziak <<a href="mailto:piotr.szwedziak@zmb.uzh.ch">piotr.szwedziak@zmb.uzh.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal">Dear All,<u></u><u></u></p>
<p class="MsoNormal">We have realised that the electron beam of our Glacios G2 (installed in December 2023) is not stable – for instance switching from imaging to diffraction and back causes the beam to return to a different position and continue drifting for
several minutes. More background information:<u></u><u></u></p>
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</span></span><u></u>switching on/off active electromagnetic field cancellation system doesn’t make a difference to the beam stability<u></u><u></u></p>
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</span></span><u></u>opening/closing the microscope enclosure, disturbing the electromagnetic field intentionally doesn’t make a difference to the beam stability<u></u><u></u></p>
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</span></span><u></u>a lower end EM (Talos 120), which is next door and in similar electromagnetic field environment, has a very stable beam that doesn’t drift
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</span></span><u></u>the drift we observe on the Glacios G2 is particularly severe after changing microscope magnification/switching to diffraction<u></u><u></u></p>
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</span></span><u></u>the beam drift is unidirectional rather than in random orientations<u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Therefore we believe the issue of the unstable beam is system- rather than environment-related. Has anyone experienced similar problems?
<u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Best and many thanks,<u></u><u></u></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Piotr <u></u><u></u></p>
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<p class="MsoNormal"><span>-- <br>
Piotr Szwedziak, PhD <br>
Center for Microscopy and Image Analysis <br>
University of Zurich <br>
Winterthurerstrasse 190 <br>
CH-8057 Zurich <br>
Switzerland <br>
<br>
</span><span lang="DE-CH"><a href="https://urldefense.com/v3/__https://www.zmb.uzh.ch__;!!Mih3wA!BgqpzTo-2WBAwsfCCK3jlKhiuaqeltrSgddXo-y0pzPcd8ipwK2HMEs0Sv7BLcvO-_CHP6izkwjHFdcKl7GmEPqnQqvGMnN54g$" target="_blank" rel="noreferrer"><span lang="EN-GB" style="color:blue">https://www.zmb.uzh.ch</span></a></span><span><u></u><u></u></span></p>
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