[3dem] spatial coherence on a Talos Arctica

[Joaquín Otón]

Hi Wim,

there's another factor contributing to coherence: from the image 
formation point of view, the ratio between numerical apertures of 
condenser and objective lenses defines a coherence degree. It leads to 
partial coherence imaging process even for totally incoherent sources. 
If source is partially spatially coherent, then both effects add.

Best,

Joaquín



On 1/23/24 13:58, Hagen, Wim J. wrote:
>
> Hi,
>
> Spatial coherence depends on gun brightness and dose rate, for typical 
> cryo-EM settings on Thermo Fisher FEG systems, one ends up with just a 
> few microradians max.
>
> Best,
>
> Wim
>
> *From:*3dem <3dem-bounces at ncmir.ucsd.edu> *On Behalf Of *Morgan, David 
> Gene
> *Sent:* 22 January 2024 23:02
> *To:* 3dem at ncmir.ucsd.edu
> *Subject:* [3dem] spatial coherence on a Talos Arctica
>
> *CAUTION:*This email originated from outside of Thermo Fisher 
> Scientific. If you believe it to be suspicious, report using the 
> Report Phish button in Outlook or send to SOC at thermofisher.com.
>
> Hi,
>
> Has anyone thought about or even measured the spatial coherence of a 
> Talos Arctica at different spot sizes?  We see something odd when 
> changing spot size that could be anything from operator error to 
> spatial coherence to issues with our FEG...
>
> -- 
>
>     politics is more difficult than physics.
>
>                                A. Einstein
>
> David Gene Morgan
>         Electron Microscopy Center
>              047E Simon Hall
>              IU Bloomington
>           812 856 1457 (office)
>           812 856 3221 (3200)
> https://urldefense.com/v3/__http://iubemcenter.indiana.edu__;!!Mih3wA!EryGT5WrDjYuWUjSGPqIj83i24amthy-kyVwTawfYSrLndgFB-0vhFFptWWpL8s7t2I5LHWkKVXzeXhH$  
> <https://urldefense.com/v3/__http:/iubemcenter.indiana.edu__;!!Mih3wA!A957RsQwjjsdv3679qTn-pz0k_fpXIZvJLi3xQhdcBHYbOQPN8ZRsE3ZGVKb2LSq9vaEZvvRuKGnLHb1ePPwax4$>
>
>
> _______________________________________________
> 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/20240123/58e94d8c/attachment-0001.html>