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Hi Jeff,

See       http://en.wikipedia.org/wiki/Dark_field_microscopy

John O cited:

Vainrub, A., O. Pustovyy, and V. Vodyanoy, Resolution of 90 nm (lambda/5) in an optical transmission microscope with an annular condenser. Optics Letters, 2006. 31(19): p. 2855-2857.

This is the CytoViva adapter - mnore on that at
http://en.wikipedia.org/wiki/CytoViva,_Inc
http://www.cytoviva.com/products/microscopy-2/cytoviva-optical-performance/
http://www.cytoviva.com/wp-content/documents/CytoViva-Use-Manual-5-7-09.pdf

Vainrub and CytoViva confuse "resolution' with "detection".

See also http://www.ncbi.nlm.nih.gov/pubmed/23520500

PubMed search for:     "darkfield microscopy"    (with quotes) turned up 
194 hits, going back to 1926 - many of the early papers are on venereal 
diseases, before microtubules start appearing in 1979, 
http://www.ncbi.nlm.nih.gov/pubmed/511939 (wow - a biochem dept with a 
light microscope).

Many microscopes phase contrast turrets include a darkfield position ... 
also deliberately mismatching the objective lens and phase ring can get 
pretty good darkfield (sometimes helps to tweak condenser focus). 40x or 
higher objective lens with PhL condenser phase ring as one potential 
combination.

Biggest problem: any dust anywhere in the entire optical path also 
scatters into the detection path. some of the dust is not (readily) 
accessible. Speaking of which - on inverted scopes I tape either a 50x50 
mm neutral density filter(s) or a glass slide (or large glass coverslip) 
over the opening at the top of the condenser - decreases dust 
accumulation inside the condenser. Also lets me operate the tungsten 
bulb at a higher voltage of more stable output (I am looking forward to 
going to LEDs in the future).

Enjoy,
George


On 1/30/2015 4:44 PM, Jeff Spector wrote:
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Greetings,
>     Can someone please point me to some references involving the theory
> behind darkfield microscopy? I understand the basic idea, but all I can
> find are different iterations of the basic idea that you block most of the
> light and only image scattered light. I'd like to learn a bit more about
> technical aspects of  darkfield, i.e. what is the smallest object you can
> observe? What role do illumination power and camera exposure play in the
> quality of the final image. What role does specimen thickness/size play in
> the final image and can you discern objects of different size
> etc...
> Any help would be greatly appreciated. Perhaps I simply need to read up on
> scattering theory?
> thanks..
> -jeff
>
>    


-- 



George McNamara, Ph.D.
Single Cells Analyst
L.J.N. Cooper Lab
University of Texas M.D. Anderson Cancer Center
Houston, TX 77054
Tattletales http://works.bepress.com/gmcnamara/42