Hi all
Repost a method that I've found earlier this year, may be of interest here in the Kingdom of Stacking.
It is a stacking version of the "Polychromatic Polarization" microscopy method developed by Michael Shribak https://www.nature.com/articles/srep17340
The use, is to get colorful polarization images from small biological specimens (diatoms, insect muscles etc...) that won't give much polarization color by themselves.
The Shribak setup needs some special optics, while this stacking method can be done with a normal polarization microscope and gives the same results (but not in real-time).
The principle is to take several black and white shots with the specimen at different angles wrt. the polarizer (rotate the stage of the microscope), then stack those photos each with a different color. 3 shots may be enough. The color then represent the local orientation of the structure.
Below the illustration of the method, with a single butterfly scale. Results could come nicer with larger subjects and better skills than me, maybe with some focus stacking before the color-combination. See the images from Shribak for example.
Original thread on Microbehunter, June 2021, with more links: (edit: and thorough discussion)
https://www.microbehunter.com/microscop ... ic#p105257
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Polarization, polychromatic stacking
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Polarization, polychromatic stacking
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Last edited by patta on Sat Dec 18, 2021 1:29 am, edited 2 times in total.
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Re: Polarization, polychromatic stacking
I did follow this method closely when I was investigating OI-DIC. The Z-quartz windows had to be rather thin, I guess my calculations at the time were off, 1.2um isn't doable, 12 is a far stretch even, for the amateur of course.
The thin pipettes we pull here have tips of that size, I can't imagine grinding a piece of crystal down to anywhere near that ballpark! Did anyone attempt to contact the authors? I think they do offer conversion kits, I'd imagine a hefty pricetag.
Good to know there's a method to achieve it in post production, though tripling the work.
The thin pipettes we pull here have tips of that size, I can't imagine grinding a piece of crystal down to anywhere near that ballpark! Did anyone attempt to contact the authors? I think they do offer conversion kits, I'd imagine a hefty pricetag.
Good to know there's a method to achieve it in post production, though tripling the work.
Re: Polarization, polychromatic stacking
Yes, we contacted the author, he answers, they sell the system (add-on over Olympus stand) it costs but not crazy, like 10K$, well, not for hobby projects.Macro_Cosmos wrote: ↑Thu Dec 09, 2021 3:18 pmI did follow this method closely when I was investigating OI-DIC. The Z-quartz windows had to be rather thin, I guess my calculations at the time were off, 1.2um isn't doable, 12 is a far stretch even, for the amateur of course.
The thin pipettes we pull here have tips of that size, I can't imagine grinding a piece of crystal down to anywhere near that ballpark! Did anyone attempt to contact the authors? I think they do offer conversion kits, I'd imagine a hefty pricetag.
Good to know there's a method to achieve it in post production, though tripling the work.
In the thread of Microbehunter, we sorted out the thickness of the quartz plates to be about 10mm, so doable (well, purchasable). The flatness and precision of those plates needs to be about 1 micron, that is a bit more accurate than standard commercial plates, but doable. Those latter may work somehow for a narrow field, but then, wider field with sharp corners, as usual it costs much more.
The digital workaround, sure it's triple work, but has some perks: can be more sensitive to the tiniest birifrengence; and factors out chromatic aberrations and the absorption colors of the specimen. It also removes the issue with off-axis quartz birifrengence. Wide sharp field still asks for $$$$ objectives though, there is no way around this sad fact of life...
Re: Polarization, polychromatic stacking
You might be interesting to see a movie of playing baby squids captured by polychromatic polarizing microscope:
https://figshare.com/articles/media/pla ... ds/9733829
https://figshare.com/articles/media/pla ... ds/9733829
Re: Polarization, polychromatic stacking
I've made a couple more decent images with this method; one is with chunks of Muscovite; the color represent the direction of the birifrengence axes.
The other are polyester fibers, that are birefrengent along the fiber. Note that there is no "estinction direction".
I've made a mistake before, the three photos to be stacked should be taken at 0, 22.5 and 45 degrees.
That is because I'm not using a lambda/4 plate.
The other are polyester fibers, that are birefrengent along the fiber. Note that there is no "estinction direction".
I've made a mistake before, the three photos to be stacked should be taken at 0, 22.5 and 45 degrees.
That is because I'm not using a lambda/4 plate.
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