Tr: TR : [3DEM] Re: Why FEG?

Mikhail.Eltsov at Mikhail.Eltsov at
Thu Jun 10 12:43:27 PDT 2004

The reference data for CM120 mentioned below were obtained with so called "point mode" of LaB6 suggested in Ruiz et al. (2003). Even after reading of this paper it is not very much clear for me what is a principle of this mode and how it improves coherence. Can anyone explain?
Thanks in advance.
Mikhail Eltsov
Laboratoire d'analyse ultrastructurale
Université de Lausanne
Bâtiment de biologie
CH-1015 Lausanne
+41 21 692 42 89 ou +41 21 692 4283

>-----Message d'origine-----
>De : owner-3dem at [mailto:owner-3dem at] De la
>part de Philip Koeck
>Envoyé : mercredi, 26. mai 2004 12:13
>À : 3dem at
>Objet : [3DEM] Re: Why FEG?
>I thought some people might be interested in a follow-up of this
>discussion. (Don't tell me if your not, just ignore me.)
>I've taken some images of carbon film on our CM120 with a brand new
>LaB6-filament just to get an idea of the limitations of this microscope.
>I get information limits between 15 and 5 Angstrom depending on
>magnification and defocus (only "biological" defocus values) and the
>information limit does not improve with decreasing magnification as
>suggested by CTF-explorer. In fact the opposite is true (at least for
>constant exposure levels). Some similar data for a FEG would be
>One thing is clear: Reaching 10 Angstrom and slightly better should not
>be a problem with a well maintained LaB6 microscope.
>For the details see the link "reference data for the CM120" at
> This is a big word file
>so you have to be patient when you download it.

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