Darkfield Adapter for Whole Slide Imaging

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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Saul
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Darkfield Adapter for Whole Slide Imaging

#1 Post by Saul » Thu Jul 16, 2020 1:08 am

Found time to play with the old project, which was inspired by:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3592912/

Initial setup:

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LEDs from the top & bottom are covered with the aluminum foill (to concentrate the light to the edge of the slide). Of course, there is a dimmer.
There is a slot in the front of LEDs to place filters (pol, color, etc)

First try:
viewtopic.php?p=84323#p84323

I liked the result, next step is to place more LEDs around the perimeter, in order to have more light control.

Anybody tried this type of illumination already ?

DonSchaeffer
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Re: Darkfield Adapter for Whole Slide Imaging

#2 Post by DonSchaeffer » Thu Jul 16, 2020 2:27 am

I ordered some optical cable so I can put light directly on a subject. I also tried making a lamp cover with a narrow opening, but your device really look interesting.

micro
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Re: Darkfield Adapter for Whole Slide Imaging

#3 Post by micro » Thu Jul 16, 2020 3:12 am

How does it do with smaller subjects like rotifers?

MichaelG.
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Re: Darkfield Adapter for Whole Slide Imaging

#4 Post by MichaelG. » Thu Jul 16, 2020 7:00 am

Saul wrote:
Thu Jul 16, 2020 1:08 am

I liked the result, next step is to place more LEDs around the perimeter, in order to have more light control.

Anybody tried this type of illumination already ?
To my shame, Saul, I still have not summoned-up the courage try mounting some tiny ‘surface-mount’ LEDs that I bought last year.

[ my epitaph might well be: too much thinking and not enough doing ]

Thanks for sharing your progress.

MichaelG.
Too many 'projects'

Hobbyst46
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Re: Darkfield Adapter for Whole Slide Imaging

#5 Post by Hobbyst46 » Thu Jul 16, 2020 10:53 am

Saul wrote:
Thu Jul 16, 2020 1:08 am
...anybody tried this type of illumination already ?
Yes, in principle. Please have a look at:
viewtopic.php?f=28&t=5876&hilit=Kawano&start=30
responses No #46 #47 #58 #60 #64 of that post illustrate the idea of into-the slide illumination. I constructed it from a strip of the smallest LEDs I could find; shaded them from above and belo and even added a tiny cylindrical "collimation" lens in front of the row of lamps. Dark field results were fairly decent (IMHO). MichaelG, MicroBob, wporter, apochronaut, zzffnn and others contributed ideas.
Another gadget that I built was a 1mm quarz fiber epoxied to a filed-out 5mm superbright LED. The tip of the fiber can be aligned to shine into the slide. It works, but replicating to prepare a line of fiber tips and attach it to the slide seemed cumbersome and impractical.

Months later I won a dedicated defective oil-immersion cardiodid darkfield condenser; fixed it with optical black tapes. It yields better dark field than the DIY LED strip, at the cost of immersion oil on the slide bottom (true mess).

I am not clear about how far the innovative Kawano approach has been pursued worldwide. On the other hand, I use LED strip sideways illuminators for slightly different setups.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

Saul
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Re: Darkfield Adapter for Whole Slide Imaging

#6 Post by Saul » Thu Jul 16, 2020 7:12 pm

micro wrote:
Thu Jul 16, 2020 3:12 am
How does it do with smaller subjects like rotifers?
Did not try yet

Saul
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Re: Darkfield Adapter for Whole Slide Imaging

#7 Post by Saul » Thu Jul 16, 2020 7:26 pm

MichaelG. wrote:
Thu Jul 16, 2020 7:00 am
Saul wrote:
Thu Jul 16, 2020 1:08 am

I liked the result, next step is to place more LEDs around the perimeter, in order to have more light control.

Anybody tried this type of illumination already ?
To my shame, Saul, I still have not summoned-up the courage try mounting some tiny ‘surface-mount’ LEDs that I bought last year.
Ordered 0.5mm LEDs, still on the way from China.
[ my epitaph might well be: too much thinking and not enough doing ]
...starving from the same thing :)

Saul
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Re: Darkfield Adapter for Whole Slide Imaging

#8 Post by Saul » Fri Jul 17, 2020 9:05 pm


Saul
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Re: Darkfield Adapter for Whole Slide Imaging

#9 Post by Saul » Sat Jul 18, 2020 4:02 am

Beta version is coming - light from both sides (separate dimmers) & sample can be rotated.

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MichaelG.
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Re: Darkfield Adapter for Whole Slide Imaging

#10 Post by MichaelG. » Sat Jul 18, 2020 6:51 am

That looks promising

MichaelG.
Too many 'projects'

Traleah
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Re: Darkfield Adapter for Whole Slide Imaging

#11 Post by Traleah » Sun Oct 04, 2020 6:28 pm

Saul,
Are you still working on this project? Any updates?

Saul
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Re: Darkfield Adapter for Whole Slide Imaging

#12 Post by Saul » Mon Oct 05, 2020 4:32 pm

Traleah wrote:
Sun Oct 04, 2020 6:28 pm
Saul,
Are you still working on this project? Any updates?
Got micro leds , but did not have time to play with them. Do not expect too much from them.
Played with some masking around edges, using aluminum foil

microb
Posts: 397
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Re: Darkfield Adapter for Whole Slide Imaging

#13 Post by microb » Mon Oct 05, 2020 5:28 pm

If you use a diffuser, you could probably just do one LED.

Basically do a clear resin or cler 3D print with the semi circle moon shape and angles connecting it to a flat for one LED. Use sandpaper to scratch up and diffuse the moon edge.

If you can cut glass slide into a trapezoid, you could do the half-moon shape by lapping that edge into a copper pipe of the right diameter with diamond paste charging the copper. Silicon carbide would be faster though. Maybe tape a block of slide together and do a few at a time.

mnmyco
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Re: Darkfield Adapter for Whole Slide Imaging

#14 Post by mnmyco » Tue Oct 06, 2020 1:45 am

Maybe try using sodium silicate solution (water glass) to fill in the gaps between the led and the slide, though you left lose the rotation bit. You can also chart the wires with a thin layer of it to insulate them. I cannot remember, but adding some aluminum may make the sodium silicate have a higher refractive index. It definitely increases the melting temp.

I would buy it, 40% sodium silicate or sometimes sodium silicate 40-42 Baume (be). I have made it; NaOH, H2O and silica gel (both commercial science supply company silica gel, refrigerant grade, and the cat litter gel, vibrant life mini-crystals). It sucks to make, smells awful, and definitely does not end up the same. The kitty litter silica gel required filtering and even after concentrating did not react with anhydrous ethanol or anhydrous methanol like it should. It should polymerize to silicone rubber.

You can add talc powder=magnesium silicate or kaolin powder=aluminum silicate as a source additives. Aluminum silicate can also be obtained from the white “wool” used to insulate hot plates and other heating elements. You can also just add a small piece of aluminum foil. It will react quite violently if it is a hot solution and you probably need to filter after words. Don’t bother trying to use a sand source or any other crystalline silicate source unless you plan to heat it to a few thousand degrees.

Ratios:
30g to 40g NaOH
120g Silica gel (I would dry it in an oven first, see end of post)
100ml distilled water (100g)

I found I needed to add water and boil down until it was very thick even when heated and would form a extremely thin layer of solid silicate on the surface of the solution. I would do this with plenty of ventilation. It would be VERY dangerous to get this any of this solution in your eye(s) at any point. I imagine it would cause immediate and permanent eye damage. Also, adding NaOH to a hot solution will cause and immediate and violent boil.

If you have to filter it use a coffee filter and do it when the solution is as hot as you can handle. I have noticed that I would need to lift my filter slightly or the process would slow to a crawl.

This will dry to a very thin, very clear layer a lot like glass. Extremely difficult to clean up once dried. I am going to try to resurface some hot plates with it and glue a broken hot plate together. This is used to glue ceramics, fyi. Diluted and mixed with glycerol it is used to form a water-soluble layer on skin, like a glove that it applied as a liquid. All kinds of uses. Including all inmounting mediums ( https://www.mobot.org/plantscience/resbot/Meth/WGG.htm)

MNMyco

From Delta Absorbents:
Oven re-drying method (preferred): Deposit 2 pounds (1 quart) of silica gel or molecular sieve in Pyrex baking dish; spread an even layer in the dish. Program the oven at 275°F. Leave the oven door slightly ajar and bake for about 1 ½ hours.
https://www.deltaadsorbents.com/Blog/Po ... ular-sieve

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