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Diatom in air under composite illumination
Posted: Fri Jul 30, 2021 3:16 pm
by Hobbyst46
My top-illumination photos of diatoms are riddled with strong glare.
So here is a small experiment to catch a 3D view of a large diatom. It is a ~300um Pinnularia (tentative) from Northern Germany. Placed as is (no glue, no mountant, no coverslip) on a 1mm thick dichroic mirror, itself placed flat on top of an ordinary slide. Plan 25x0.45 objective. Transmitted light: a polarizing filter within the microscope head, another polarizer on the light source. Top illumination: a LED ring around the objective. Stack of 10 images. Some tweaking of contrast and brightness.
Re: Diatom in air under composite illumination
Posted: Fri Jul 30, 2021 6:13 pm
by perrywespa
Nice, interesting image.
Re: Diatom in air under composite illumination
Posted: Fri Jul 30, 2021 7:30 pm
by Hobbyst46
Thanks, perrywespa.
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 3:47 am
by Javier
Very interesting project and a beautiful image!
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 7:30 am
by Hobbyst46
Thanks Javier.
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 2:27 pm
by BramHuntingNematodes
Were you holding your breath the whole time?
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 3:19 pm
by Hobbyst46
Diatoms strongly attach to glass surfaces by virtue of electrostatic forces. Even if you invert the slide, the diatom is likely to stay and not fall off. No need to hold my breath during the session - the diatoms never moved. My only concern was that tiny fibres and dust particles could gather around it (to watch and enjoy the jewel
).
On other occasions, I prepared cover-glass topped chambers for diatoms in air.
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 8:34 pm
by hans
Interesting colors, is the cyan background the color reflected from the dichroic mirror and the red/orange transmitted? Or the other way around?
Re: Diatom in air under composite illumination
Posted: Sat Jul 31, 2021 8:49 pm
by Hobbyst46
hans wrote: ↑Sat Jul 31, 2021 8:34 pm
Interesting colors, is the cyan background the color reflected from the dichroic mirror and the red/orange transmitted? Or the other way around?
Thanks.
The other way around: cyan is transmitted (it is a short pass filter; transmits 400-550nm, reflects >550nm) and the red/orange is reflected top-illuminator light, yielded by warm-white LEDs.