Hi guys,
This image was taken using a Fr-TIR device that delivers a quite broad angular beam. The following image brings two types of pollen plus some debris due to my sloppy preparation. One, the small, is extremely reflective. May this be Kramers-Kronig? The other looks semitransparent. I kind of like the warm color that this image has.
Ramon
5x 3 small.jpg
Hello Ramon,
Let me guess the small (bright) ones are from some pine tree, and the bigger ones look a little like Dandelion.
This looks more or less like the typical appereance of this kind of pollen in Darkfield.
Pine Pollen has two air filled sacks attached to it's surface which causes light to be reflected towards the objective.
So they look bright in classical DF as well.
Interesting, here is that you can see some detail of the surface of the bigger yellow pollen grains.
The little dots there. This may be caused by the low angle of your device.
Greetings Holger
Hi Holger
Zitat von: Spectrum in Juni 13, 2026, 08:23:11 VORMITTAGLet me guess the small (bright) ones are from some pine tree, and the bigger ones look a little like Dandelion.
Yes, the small one is pine. The big one I just picked randomly.
Zitat von: Spectrum in Juni 13, 2026, 08:23:11 VORMITTAGThis looks more or less like the typical appereance of this kind of pollen in Darkfield.
In normal Darkfield is as reflective as with Fr-TIR? I will try.
Zitat von: Spectrum in Juni 13, 2026, 08:23:11 VORMITTAGPine Pollen has two air filled sacks attached to it's surface which causes light to be reflected towards the objective.
This is exactly the same response that Rik from Photomracrography.net gave me. BTW in this image I used glycerine (n=1.47) as index matching media.
Zitat von: Spectrum in Juni 13, 2026, 08:23:11 VORMITTAGInteresting, here is that you can see some detail of the surface of the bigger yellow pollen grains.
The little dots there. This may be caused by the low angle of your device.
I will invertigate.
Holger, at last the Beam Splitters arrived. Literally right now. You have to walk me throught the experiment at hand.
Be well
Ramon
Hello Ramon,
If this experiments should be of value, it is important to keep variables as steady as possible.
Your device is highly dependant on the refractive index of the medium you use.
Switching between water and glycerine makes a difference here.
So if you want to see effects like "Frustrated Total Reflection", "Kramers-Kronig effects" or fluorescence similar to TIRF (if there are any of them at all...)
you have to take care of following parameters:
-objektive/magnification:
Name the magnification and avoid cropping, and use at least one (10x) magnification as a standard to begin with
-White balance of your camera:
This should be fix for all of the pictures you want to compare.
This is very important to avoid color artifacts!
-Exposure time
This can not be fixed because that would lead to over or underexposuer like your pine pollen picture, for example.
So please use an exposure where all the highlights in your frame are rendered but tell us the used exposure time under the picture.
-Distance between specimen and cover slip
This is (as already said in another thread) very important for the effect you named your device after. If there is any Frustrated Total Internal Reflection effect, it will only appear if the specimen is squezed firmly to the surface of the cover slip, so that parts of it come in very close contact with the cover slip.
That's another reason why you should use destilled water as a mountant...
The water evaporates after some time, pressing the specimen more and more on the illuminated surface
(cover slip). Especially soft specimen like pollen, for example.
So watch what happens during that time, and record any change via video or a row of pictures.
Interesting are surface structures witch are close to the cover slip that appear during drying,
or change apperance during drying,
or change colour during the "dry out time".
-Also advisable:
Don't spread your pictures on several threats.
Post your test serie for all your transparent test specimen in one thread, preferable next to each other.
That makes the comparison much easier.
Best Holger
Hallo Ramon and Holger,
Zitat von: SpectrumLet me guess the small (bright) ones are from some pine tree, and the bigger ones look a little like Dandelion
Dandelion pollen is smaller than pine pollen. It is also not as round as a ball. Look here: Taraxacum officinale (https://pollen.tstebler.ch/MediaWiki/index.php?title=Taraxacum_officinale).
Best regards Gerd
Hi Holger
Zitat von: Spectrum in Juni 13, 2026, 20:41:48 NACHMITTAGS-Distance between specimen and cover slip
This is (as already said in another thread) very important for the effect you named your device after. If there is any Frustrated Total Internal Reflection effect, it will only appear if the specimen is squezed firmly to the surface of the cover slip, so that parts of it come in very close contact with the cover slip.
That's another reason why you should use destilled water as a mountant...
I am having problems with the setup of the Fabry-Pérot interferometer. The oil under the cover slip spreads out and seals the interface cover slip/water/beam splitter. Hence the water dont evaporate. I will try an fix it. Any ideas??
Cya
RamonFabry-Pérot interferometer.jpg
Hello Ramos,
For cleaning up the oil mess:
Put the coverslip together with the mirror in isoprop or acetone. It's advisable to take it there as a whole, because if you move the mirror sideways on the glass plate, you most likely scratch it's delicate surface. Submerge it completely in a vertical position.
With a little bit of luck the two plates fall apart in the solution.
Then you could pick up the mirror carefully with a tweezer (a plastic tweezer would be nice) at an edge, and rinse it further with isoprop or acetone.
As a last step use very clean solvent or lens cleaning solution to rinse away the last Remakes of oil.
Don't rub the surface of the mirror with anything, lest you scratch it!
Greetings and good luck, Holger