Epi DIC for Biology?

[Pau]

I'm setting up an epi DIC system with old parts from Leitz and Zeiss (as usual ). I still need to figure a permanent light source, likely with fiber optics, but in my preliminary tests using an Ikea LED lamp it's working.

The view of metalurgical specimens looks very promisng, but I'm more interested in biological ones.

Searching both the forum and google I don't find images of biological subjects with this technique and my only tests using plant leafs aren't very encouraging.

Microscopyu also only consider metalurgical and electronic specimens.
http://www.microscopyu.com/articles/dic/reflecteddic.html

Does anyone have experience or info about it?
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Pau

[rjlittlefield]

As I understand it, DIC relies on polarization to keep the two optical paths separate. If anything destroys the polarization, it also destroys the DIC effect. I'll bet with your bio specimens you're only getting DIC from specular reflections, since non-specular reflections will be also non-polarized.

--Rik

[Chris S.]

Pau, I don't have any additional knowledge or experience, but I'll mention that I share your interest and have it on my list to pursue this as well. Several months ago, I purchased three Nomarski prisms, but have yet to integrate them into my setup. It certainly looks straightforward. I haven't looked in a while, but found the writings of Nomarski and others who popularized the technique some decades ago to be much more informative than the current marketing literature of the microscope companies.

Like you, I searched for images taken with the technique, and found some that made me think it would be a useful tool, but none of these were of plant subjects.

My expectation is that episcopic Nomarski illumination may be really useful for subjects that don't change the polarization state of light, but not too useful for things like plants. I shoot a fair number of man-made objects, and am looking forward to seeing what the technique does with some of them.

Cheers,

--Chris

[Pau]

Rik and Chris, thanks for commenting,

I think you're right (unfortunately for my initial purpose ).
The image of the leaf surfaces is very similar to cross polarization at zero shear and adding shear when translating the Nomarski prism just adds reflections and lowers contrast (and slighly changes the color).
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Pau

[Charles Krebs]

Pau,

Very limited experience with this, but it has never showed me anything very interesting with biological specimens. Computer chips and similar subjects yes, biological specimen no.
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http://www.krebsmicro.com

[Ecki]

EPI DIC does not work with biological samples. It can only be used with metallic surfaces.

For biological samples EPI darkfield ist the best choice.
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www.wunderkanone.de
www.flickr.com/wunderkanone

[Pau]

Thanks Charles and Ecki,

With my few epiplan DIC objectives I can't get epi darkfield but I can do epi cross polarization. The project is now parked but I plan to resume it in the future.
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Pau

[curt0909]

I can confirm it will not work with most biological specimens. Possibly a metallic insect but I have yet to try this. It is very helpful for imaging metals though.