[labnetwork] SEM Liner Tube Voltage Issue

[Philipp Altpeter]

Dear Nicki,


We had a similar issue with an old Zeiss 982 a while ago. Besides the 
strange rotation, we also observed a substantial difference in actual 
focus vs. shown WD.


A few things that you can do before you replace the 8kV power supply:


In case of our DSM 982 Gemini column, the liner tube can slide down and 
can create a short to ground with the end cap of the objective lense. 
You can carefully remove the end cap and check, wether or not the liner 
tube is sticking out a little bit, touching the cap. This can happen 
over time, or if the system was moved recently.


Also, if there are other devices using 8kV, e.g. a beam blanking unit, 
you might want to unplug them (including the inlense) and test without 
them being connected.


We found that a high voltage relais didn't work properly.


I hope this helps.


Philipp






Am 03.03.2025 um 23:08 schrieb Nicki Shaw:
> Hello,
> We are troubleshooting a SEM column issue on our FIB-SEM following a 
> planned power interruption. In short, any advice regarding the 
> disassembly of a *Gemini SEM column *or liner tube 
> troubleshooting/maintenance would be greatly appreciated.
> The tool in question is a ZEISS Auriga 40, and we have observed the 
> following:
>
>  *
>     The SEM image is significantly rotated relative to the expected
>     alignment, despite the scan rotation being off.
>  *
>     The Inlens detector does not get a signal, but the SESI detector
>     gets a signal with some apertures. The emission view shows that
>     the apertures are significantly misaligned, despite no manual
>     changes being performed.
>  *
>     The image rotation improves as SEM voltage is increased, becoming
>     nearly correct at 21 kV—at which point the liner tube shuts off.
>
> During troubleshooting, we measured the liner tube voltage:
>
>   * When running the liner without connecting it to the column (with a
>     resistor in place to draw current), the voltage ramps normally.
>   * When the liner is connected to the column, the voltage plateaus at
>     600–700 V instead of reaching the expected 8000 V.
>
> We have checked:
>
>   * The liner tube cable and relay box connections.
>   * The power module and associated lens control boards.
>
> Given these observations, it seems likely that there is a voltage leak 
> inside the column affecting the liner tube voltage. Has anyone 
> encountered a similar issue, or can provide insight into further 
> troubleshooting steps? We are considering opening the column to check 
> for a short but have not attempted any disassembly other than 
> replacing the filament.
> Any advice would be greatly appreciated!
> All the best,
> Nicki
> Senior Facility Microscopist
> Quantum-Nano Fabrication and Characterization Facility (QNFCF)
> 200 University Ave W | Waterloo, Ontario | N2L 3G1
> Office: QNC 1611
> P: +1 519-888-4567 ext. 42022
>
> _______________________________________________
> labnetwork mailing list
> labnetwork at mtl.mit.edu
> https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20250304/29f2eb23/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Outlook-5ljex2pj.png
Type: image/png
Size: 11993 bytes
Desc: not available
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20250304/29f2eb23/attachment.png>