Diatoms in epi DIC

Images made through a microscope. All subject types.

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Scarodactyl
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Diatoms in epi DIC

Post by Scarodactyl »

I recently bought a couple slides from Diatom Lab so I'd have a good subject to look at in a future (likely futile) project of diy transmitted DIC. I've been having fun with these, looking at them with my new Leica "Rottermann contrast" base (which is basically a tunable oblique system for low magnifications). I also put the slide under my main scope and was surprised to get what looked like pretty good contrast using epi DIC.
Imagediatoms in epi DIC by Stephen Challener, on Flickr
Taken with one of the cheap Nikon 20x/0.75 plan apos, pushed up to 40x with my mag changer.
I think this would look better if I weren't having some vibration issues with my table--still, I am pretty happy with the look. I had fun with oblique/darkfield but this is definitely more dramatic.

Macro_Cosmos
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Re: Diatoms in epi DIC

Post by Macro_Cosmos »

Looks pretty good! I like the results, why are you tempting me on reflected light DIC? #-o

DIY transmitted light DIC isn't that hard, measuring the back focal plane of dry objectives isn't trivial but not exactly hard. Oil immersion is a different story. With say a U-DICT and a U-ANT installed, you can figure a mechanism to translate the slider and place it exactly at the back focal plane of whichever objective you like of whatever brand. The big 4's "normal" DIC slider have almost identical shears, they are interchangeable. Do the same for the condenser prism too, a condenser such as the U-SC (or cheaper BH2 version) would work nicely, you have sufficient space between the top lens and the rear which is probably an optical flat that's AR-coated.

The cheap 20x (not VC) Nikon Plan Apo objectives require a 0.4mm coverslip, try find an optical flat of the same thickness, or rather around 0.3 so there's 0.1mm tolerance for water film.

Scarodactyl
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Re: Diatoms in epi DIC

Post by Scarodactyl »

I appreciate that! I doesn't hold a candle to your results with transmitted DIC but it will benefit from further experimentation.
Thanks for the tips! That should be a fun project, though I need to clear off what's already on my plate first.
Just to be clear, this is one of the cheap normal label 20xes, rather than the bronze barrel oem ones.

Didier_Micro
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Re: Diatoms in epi DIC

Post by Didier_Micro »

Hello,
The marriage of orange and silver colors on the black background is successful and unusual.
A higher magnification with more details of the diatom could be great ?
Regards
Didier

Scarodactyl
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Re: Diatoms in epi DIC

Post by Scarodactyl »

Here's a shot with my 40x/1.0 water immersion objective, which definitely has better resolution, and not just because of the higher NA--because of the splitting and separation of the two images before recombination epi DIC kind of puts its own separate limits on pushing up magnification above the prism.
Image
This is not a Nikon objective, so the DIC isn't quite as good. I'm also really not very good at stacking these.
In comparison this is what epi bright field looked like:
Image
Just for kicks, here are some shots using that Leica base I mentioned earlier, using my Olympus 20x SApo mounted on my Leica Z6, pushing mag up to 40x. The base iis meant for stereo microscopes and I got better results with this objective by stopping the Z6's iris down a bit. Note the stacking is significantly worse even than above because my Z6 is mounted on an Olympus coarse/fine focus mount which is definitely not meant for such thin subjects.
With oblique light:
Image
And using the fancy tunable oblique "rottermann contrast (tm)":
Image
Image

Lou Jost
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Re: Diatoms in epi DIC

Post by Lou Jost »

I think these look really nice, even the ones you were unhappy with.

Scarodactyl
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Re: Diatoms in epi DIC

Post by Scarodactyl »

Thanks, I appreciate that!
Just in case anyone is interested, thr seller I got my rottermann/oblique base from has two more up for sale. This is the only time I've seen them offered.
https://www.ebay.com/itm/R176857-Leica- ... 4068231912

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