[3dem] Peculiar Glacios Issues

[Christopher Aylett]

Dear All,

Many thanks for all the feedback people have provided - I summarise the points made and updates below.

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On the autoloader issue:

- Several people have commented that the clip-rings might have been loaded upside-down, although I am unclear how they might have gauged that from the images provided; the bent clip-rings I have been shown demonstrated both bending topologies, i.e. both C-ring side in and C-ring side out, although there should be a preferred bending direction as the gripper opens one side only. I have been told that our facility manager (an ex-engineer) and an engineer loaded the clip-rings in question and were aware that topology needed to be preserved, but loaded the wrong way up because of "errors in training materials”. Obviously it should go without saying that one should load the clip-rings in the correct orientation.

- I have been told by an autoloader engineer that;

“Significant force would need to have been applied to cause the damage experienced and the damage was only visible once the axis had been removed from the autoloader” - furthermore, it was their opinion that - “this damage could not possibly have been caused by the autoloader itself” - as the automatic cut-out would have prevented the low-torque electric motor from continuing to move the axis.

… I would therefore hope that it is unlikely any other instrument would suffer from similar issues, and do not think it worth soliciting further input with respect to this from the lists.

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On the drift issue:

- It is clear from feedback that all the salient points suggest a lens temperature effect, most likely a flow imbalance.

- It has been highlighted that chiller and column temperature must be within 1 degree centigrade, or drift will result, although such balancing had already been performed in our case. We have had a series of unprecedented air conditioning failures since commissioning, however, which would certainly have contributed to variation in drift, although the issue remains ongoing even when the air-conditioning has stabilised.

… if anyone is aware of any way in which such a lens imbalance can have arisen without changes in lens coolant flow, which I have been repeatedly assured could not possibly have occurred, then I would be grateful to hear from you.

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Many thanks everyone once again for their help -

Best wishes,

Chris

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Chris Aylett - Ph.D

天网恢恢 疏而不漏

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> On 22 Sep 2021, at 14:15, Christopher Aylett <chsaylett at gmail.com <mailto:chsaylett at gmail.com>> wrote:
> 
> Dear EM mailing lists,
> 
> We received our new Glacios from Thermo / FEI this summer, and initial commissioning proceeded extremely smoothly, however we have experienced several quite unusual and peculiar issues shortly after beginning user operation which I would like to run past the lists in case anyone has any insight into their possible underlying cause.
> 
> Autoloader issue (currently resolved by gripper arm replacement, but severe and of unconfirmed initial cause):
> 
> While the autoloader had been working perfectly during commissioning, following an initial initialisation error, the autoloader stopped registering clip-rings placed within it. Our facility manager was able to confirm that no grids or clip-rings had been dropped into either the column or autoloader itself, however there was clear mis-alignment (see attached video). We then had a series of more severe failures; the clip-rings were being bent into U-shapes apparently, although this was not through being pushed into the cassette, which was my initial assumption, as the dimensions do not match - some are too large, some too small. There does not appear to be any damage to our cassettes, so maybe the gripper jaws were clamping them down into this shape, although they should not open wide enough to allow that to the best of my understanding? I am still at a loss as to how this happened, and while it seems to have been resolved through replacement of the gripper arm by Thermo / FEI, I would like to find out what went wrong in the first place so that we can be certain it does not recur. I attach images in case they are helpful.
> 
> Drift issue (ongoing - intermittent and of variable severity):
> 
> While drift rates during commissioning were effectively zero (consistently below 0.2 Å/s with the stage at rest), we are now experiencing ongoing image drift which began suddenly shortly after commissioning completed, varies between 1 and 5 Å/s in rate, and is predominantly (but not exclusively) in the X direction, suggesting lens involvement. The drifting issue remains present despite one hour of stage rest. Our chiller was purchased from ATC rather than Thermal Exchange as is typical, however extensive monitoring of temperature has implied that both room temperature and chiller water temperature are stable within specification, and performance was admirable during commissioning. The drift appears to increase very distinctively once imaging commences e.g. a drift test begins, as can be seen in the attached drift test image, before plateauing. I have been assured that there has been no change in lens coolant flow / balance since installation, however.
> 
> Thermo / FEI have been responsive in fixing broken parts, and Paul - our facility manager - has been investigating matters, however we still lack explanations for either underlying issue. Should anybody have experienced similar issues with their own microscopes, or be able to provide probable diagnoses, we would be most grateful to hear from you - 
> 
> Best wishes,
> 
> Chris
> 
> #######################################
> 
> <clipring_lineup.png>
> <clipring_toolarge.png>
> <clipring_toosmall.png>
> <increasing_drift_test.png>
> <autoloader_failure.mp4>
> 
> #######################################
> 
> Dr. C. H. S. Aylett
> 
> Principal Investigator and Sir Henry Dale Fellow
> Imperial College London
> 
> #######################################
> 

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