[3dem] Pre-Specimen Shutter (Yu, Xiaodi [JRDUS])

[Wim Hagen]

Tecnai and CM microscopes did not have a dedicated coil to blank the beam pre-specimen, so the gun deflector coils where used to blank the beam, hence "Gun Deflector (beam blanker)". Since deflector electronics were noisy at the time, they were filtered and thus slow, which could be seen when opening the column valves on a e.g. normal Tecnai: the beam would slowly move in from the side of the screen.  On cryo-systems the gun deflector electronics filter was removed so it was fast enough for blanking purposes, but you didn’t want to do STEM on those systems as the noise on the gun coils would ruin things. On Titan systems a true dedicated blanker coil was introduced, hence "Gun blanker (pre-specimen shutter)", but some parts in software still use the gun deflection coils, hence a confusing mix of things, depending on which software one uses to control the camera. Talos/Glacios does not have a dedicated blanker ("Gun blanker (pre-specimen shutter)”), everything is still done through the gun deflection coils ("Gun Deflector (beam blanker)”). All the newer scopes have better deflection electronics, so no filtering needed, so shuttering is fast enough, so far….
Best,
Wim

> On 24. Jun 2020, at 03:19, Matthews-Palmer, Teige <t.matthews-palmer14 at imperial.ac.uk> wrote:
> 
> Can anyone explain the difference between Gun Deflector (beam blanker) and Gun Blanker (pre-specimen shutter)?
> Gun Blanker sounds either like a mechanical shutter hardware option not installed; or part of the Gun Deflector - but then why is it a separate device in the microscope control software?
> 
> Grateful for any explanations!
> Teige
> 
>> On 24 Jun 2020, at 02:02, Jason Kaelber <jason.kaelber at rutgers.edu <mailto:jason.kaelber at rutgers.edu>> wrote:
>> 
>> This email from jason.kaelber at rutgers.edu <mailto:jason.kaelber at rutgers.edu> originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list <https://urldefense.com/v3/__https://spam.ic.ac.uk/SpamConsole/Senders.aspx__;!!Mih3wA!VFParMj59ZHBcjRq4bZfapb6-MrwsKanClm_O9bCr_8yFnjrCicS3CNQKZ0L4R0o_Q$> to disable email stamping for this address. 
>>  
>> Hello Xiaodi,
>> The Blanker/Shutter Monitor window is showing what you would expect it to show if everything is working. When the deflector coil (pre-specimen shutter) is displayed as orange (N/A), the Blanker/Shutter Monitor window does not know the instantaneous state because it is controlled by the camera.
>> Unfortunately you would also see the orange if it's almost working but the camera is not controlling the blanking correctly (very rare).
>> Cheers,
>> Jason
>> 
>> *******************
>> This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. 
>> If you trust the sender, add them to your safe senders list https://urldefense.com/v3/__https://spam.ic.ac.uk/SpamConsole/Senders.aspx__;!!Mih3wA!XnHA7SFIxZ8c4VRcAhunCqByJFP1wGRDVy5Y3CgWW4Etf2CW2ptOPjLpWDz6Cf6uFw$  <https://urldefense.com/v3/__https://spam.ic.ac.uk/SpamConsole/Senders.aspx__;!!Mih3wA!VFParMj59ZHBcjRq4bZfapb6-MrwsKanClm_O9bCr_8yFnjrCicS3CNQKZ0L4R0o_Q$> to disable email stamping for this address.
>> *******************
>> _______________________________________________
>> 3dem mailing list
>> 3dem at ncmir.ucsd.edu <mailto:3dem at ncmir.ucsd.edu>
>> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem <https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem>
> _______________________________________________
> 3dem mailing list
> 3dem at ncmir.ucsd.edu
> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.ncmir.ucsd.edu/pipermail/3dem/attachments/20200624/3798e84d/attachment.html>