[3dem] spatial coherence on a Talos Arctica
Joaquín Otón
joton at cells.es
Tue Jan 23 05:52:41 PST 2024
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
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>
> 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
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