Soil shadowing microscopy question

Hi all
I want to use the microscope to look at soil samples and it seems like the optimum setup should include an Abbe condenser 1.25 N.A and Iris diaphragm.
Do you think this is something that can be added to de ofm? I have seen some 3d printed iris diaphragms on thingiverse
Do you know a different approach for shadowing microscopy?

In theory, you can attach pretty much whatever you like to the condenser mount - but in practice I suspect most high-NA condenser assemblies will be too heavy for that mount. I think the key thing would be to find lenses that can be assembled into an illuminator with a high enough NA - that might mean sourcing the condenser lenses used in a standard condenser, and printing a smaller, lighter mount for them - or indeed making a more rigid mount to attach one of those to the OFM.

Presumably if you need that NA, you are working with a very high NA 100x objective? I must admit “shadowing microscopy” is not a term I’ve come across in optical microscopy before - could you explain a bit more what you mean by it?

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Hi Richard
Thanks for your answer.
I believe that by shadowing (the term was used in a course for non technical people in a soil microscopy course) they mean differential interference contrast microscopy. I’m not an expert neither so… I think the idea is to enhance the contrast in unstained transparent samples that you can find in soil. I’m working with the 16mm diameter 40x /0.65NA chinese objective.
Maybe there is another way to enhance contrast?
Thanks again

ah ok - if you’re using a 40x objective I don’t think you will benefit much from a 1.25NA condenser, in fact it might decrease your contrast. We ran a student project last year to implement something akin to DIC or phase contrast in the openflexure microscope, the reports are in an issue thread. It would be very nice to get this integrated into the main microscope designs - but it’s not currently top priority for anyone.

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Thanks Richard.
I will look into the issue thread you mention and get back to you.
Maybe I can dedicate some time to implement this

Try to light the slide with a parallel beam rather than a converging beam. I tried through a hole in the foil without a condenser lens about 0.4-0.5mm (image width on my microscope at 40x is 0.355mm).
although it degrades the depth of the image by projecting into a flat picture, it significantly increases the contrast in my case.

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Dark field microscopy is also good on transparent materials. It shows up edges well. The illumination is easier than DlCand it does not need processing. It does not give as much information though.