Anyone knows why this is happening?

Images made through a microscope. All subject types.

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pwnell
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Anyone knows why this is happening?

Post by pwnell »

It is a piece of algae photographed under polarized lighting. The first image is feflected polarization, the second is transmitted polarization. What is the white/purple band in the middle of the filament in the reflected polarized shot and why is it not in the transmitted polarized photo?

Image
Tropical Aquarium algae, 40x, EPI-POL

Image
Tropical Aquarium algae, 40x, Transmitted POL

Cactusdave
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Post by Cactusdave »

Do you have a coverslip over the algae?
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pwnell
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Post by pwnell »

Yes I did.

Jacek
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Post by Jacek »

interesting .... ?

Ecki
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Post by Ecki »

I think this is the top of the filament.

Cactusdave
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Post by Cactusdave »

I'm guessing that in the epi-polarising picture there is reflection from the upper surface of the algal filament, which is behaving like a shiny cylinder. The blue colour is presumably due to some retardation effects on the polarised light. I'm a little surprised that the effect should be so strong with a coverslip in place which would tend to flatten the upper surface of the cylindrical algal filament. It would be interesting to see if the effect changes or disappears as the preparation dries out and the coverslip presses more strongly on the filament. Some algae deposit considerable amounts of calcium salts in their cell wall making them incompressable and this could also be a factor in the effect you are seeing. An image of a larger portion of the alga wold be helpful in trying to identify it.
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear

pwnell
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Joined: Fri Dec 18, 2009 4:59 pm
Location: Tsawwassen, Canada

Post by pwnell »

Here is a DIC and fluorescent closeup (40x), and a dark field @ 10x.

Image

Image


Image

Cactusdave
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Location: Bromley, Kent, UK

Post by Cactusdave »

This is very similar to an alga I see in the UK. Unfortunately I don't know it's name. We are blessed with lots of subject experts on the forum, but I thing we need to recruit an algologist. :lol:
Leitz Ortholux 1, Zeiss standard, Nikon Diaphot inverted, Canon photographic gear

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