FTIR used on biological specimens mounted on a slide provides a singular illumination pattern that highlights features of the specimen that otherwise would not be visible.
I took this image using a FTIR device that I developed. I call it Dimomo. It is a stack of 20 images.
Together with the FTIR image find the brightfield image.
Find full resolution image at the link: https://drive.google.com/file/d/14n-9r5na_fIIYEH3U8wbO0NVPqceXaVc/view?usp=sharing
B RGDS
Ramon
Silkworm 1 small.jpg
Silkworm bright small.jpg
Hi Ramon,
nice to meet you, i have some questions.
You are observing silkworms.
Normally, they are opaque.
You are using FTIR, or Fourier-transform infrared spectroscopy, a method for obtaining information about the chemical composition.
So you use the lighting from this FTIR device to take better photos and look inside the pupa?
Can't you see through a silkworm with a normal light microscope, or are the reflections too strong?
Or is it more of a kind of reflected light microscopy (epi-illumination)?
Best regards
Rudolf
Zitat von: rlu in Mai 22, 2026, 09:10:44 VORMITTAGFTIR, or Fourier-transform infrared spectroscopy
Bildschirmfoto 2026-05-22 um 14.07.12.jpg
I think these are two different methods ...
Zitat von: rlu in Mai 22, 2026, 09:10:44 VORMITTAGYou are using FTIR, or Fourier-transform infrared spectroscopy, a method for obtaining information about the chemical composition.
Hi Rudolf. FTIR stands for Frustrated Total Internal Reflection. As is pointed out by Peter.
Zitat von: rlu in Mai 22, 2026, 09:10:44 VORMITTAGSo you use the lighting from this FTIR device to take better photos and look inside the pupa?
Since, I think, is a new system of illumination. I am using it on all kinds of samples, be it transparent or opaque.
Zitat von: rlu in Mai 22, 2026, 09:10:44 VORMITTAGCan't you see through a silkworm with a normal light microscope, or are the reflections too strong?
As you can see in the brightfield image of the silkworm there is an area that it is opaque. With a trans illuminated microscope you can not see opaque samples. With the FTIR device I use you can see transparent and opaque samples. For example, I do metallography with my old biological microscope.
Zitat von: rlu in Mai 22, 2026, 09:10:44 VORMITTAGOr is it more of a kind of reflected light microscopy (epi-illumination)?
Its both epi and trans illumination. It depends on how you assemble it in the microscope.
You can find all the info on the FTIR device I use in the link: https://drive.google.com/drive/folders/17zpLael8OpDQ5c37_7FOTJiKIPID75xI?usp=sharing
I attach two photos, one is used as epi illumination and the other as trans illumination.
Be well
Ramon
Setup-Dimomo.jpgDimomo 1.jpg
@ Off-Topic an:
Abkürzungen können ihre Tücken haben.
Aus dem Medizin-Alltag:
HWI kann bedeuten
- Hinterwandinfarkt
- Harnwegsinfekt
- Häufig wechselnder Intimverkehr
und ist außerdem auch das Kennzeichen einer nord-ost-deutschen Hansestadt. ;D
@ Off-Topic aus.
Zitat von: Jürgen Boschert in Mai 22, 2026, 16:22:38 NACHMITTAGSAbbreviations can be tricky.
I developed this device years ago and just recently I learned that the principle it uses is FTIR. It was brought to my attention by an expert microscopist in Photomacrography.net forum.
I presented the device in Photomacrography.net forum few weeks ago. I was expecting that people there would be interested in exploring opaque samples with their biological microscopes. For example exploring the surface texture of metals. But contrary to my expectations people were more interested in its use in biological samples due its singular way of illumination.
I look forward to hear the comments of the community.
Ramon
PD Sorry that I dont speak or write german.
Hi Ramon,
very interesting topic!
Where do you see the main field of application?
Best
Peter
Hello Ramon,
Very interesting, indeed!
That's a valid link to "Photomacrography.net"from your device, right?
https://www.photomacrography.net/forum/viewtopic.php?p=312615#p312615
The link in your post here, only lead to the Main page...
Greetings Holger
Zitat von: Spectrum in Mai 22, 2026, 19:41:28 NACHMITTAGSThat's a valid link to "Photomacrography.net"from your device, right?
https://www.photomacrography.net/forum/viewtopic.php?p=312615#p312615 (https://www.photomacrography.net/forum/viewtopic.php?p=312615#p312615)
The link in your post here, only lead to the Main page...
Hi Holger. Yes, this is the device. In the following link you can find all the info:
https://drive.google.com/drive/folders/17zpLael8OpDQ5c37_7FOTJiKIPID75xI?usp=sharing
There is a lot to see, I have been working on this device for years. You honest opinion is warmly welcome.
Zitat von: Peter T. in Mai 22, 2026, 17:08:12 NACHMITTAGSvery interesting topic!
Where do you see the main field of application?
Well, it works wonders on metallographic samples. Because of the way it illuminates it provides more information than a metallographic microscope in brightfield. You can find all the info in the link.
I attach a photo so you can compare the results. Its C10 Steel Normalizad. The image on the left its made with a metallographic microscope. The image on the right its made with a biological microscope using the FTIR light guide. The different tones that you can see in the image on the right relate to the orientation of the crystal. It provides more information. You can find the full resolution images in the link.
But it may have other applications. The light hits the sample in very shallow angles that can be useful with some type of samples. If I am honest I was expecting that people in the community can help me find applications.
For example, I attach a photo of a Honey Bee Mouth mounted on slide. In this case its sort of a blend between bright and dark field.
I really look forward that you guys find it interesting. And I would love to hear your opinions. I can provide the blueprints so that anyone can build it on their side. As I say in my introduction I applied for a patent for this device. Although I am not very confident that I will get it because is such a simple thing.
Well, I look forward to continue this conversation.
By the way, when I was younger I used to spend christmas in Germany. In Wolfenbuttel to be precise. I love the Harz Mountains!
Tecmicro-8-01_10X.jpg
Honey Bee Mouth 2.jpg
Hi Ramon,
in my view, the complementary colours you see in brightfield vs. your glazing incidence illumination are caused by the relation between absorption coefficient and reflection coefficient. In physics, these relations are dealt with by the so-called Kramers-Kronig relation: If you know the absorbance of a material over a broad wavelength range, you can calculate the reflection from that.
In consequence, this leads to the fact that a strong absorbance in a given wavelength range leads to a weak reflection in this range. This means e.g. that gold is yellow in reflection, but blue in transmission. If you have a very thin gold layer, this becomes easily visible. You can also try that out by using a blue pen and drawing a 5x5mm^2 square. If you look at this square from a small, glazing angle, the square will reflect in reddish colour.
In daily life, this phenomenon is easily overlooked, e.g. leaves are green in transmission, but also in reflection. But actually this presumed reflection is caused by scattering of the light within the leave, and not by "physical reflection" at the surface.
Jürgen
Zitat von: jcs in Mai 22, 2026, 21:27:46 NACHMITTAGSin my view, the complementary colours you see in brightfield vs. your glazing incidence illumination are caused by the relation between absorption coefficient and reflection coefficient. In physics, these relations are dealt with by the so-called Kramers-Kronig relation: If you know the absorbance of a material over a broad wavelength range, you can calculate the reflection from that.
In consequence, this leads to the fact that a strong absorbance in a given wavelength range leads to a weak reflection in this range. This means e.g. that gold is yellow in reflection, but blue in transmission. If you have a very thin gold layer, this becomes easily visible. You can also try that out by using a blue pen and drawing a 5x5mm^2 square. If you look at this square from a small, glazing angle, the square will reflect in reddish colour.
Hello Jurgen
There are a lot of physics packed in just this few sentences. Please allow me to review my notes on light-matter interactions. But let me first ask you:
Zitat von: jcs in Mai 22, 2026, 21:27:46 NACHMITTAGSin my view, the complementary colours you see in brightfield vs. your glazing incidence illumination
What images are you referring to? Regarding the image attached (Fern Leaf mounted on a slide), in the Photomacrography.net community we are having a discussion about the "green stuff" that we see in the right side image (taken with FTIR device) versus the left side image (bright field). Is that what you mean?
Fern Leave 01_10X.jpg
Zitat von: jcs in Mai 22, 2026, 21:27:46 NACHMITTAGSIn daily life, this phenomenon is easily overlooked, e.g. leaves are green in transmission, but also in reflection. But actually this presumed reflection is caused by scattering of the light within the leave, and not by "physical reflection" at the surface.
Again, let me dive into light-matter interactions to understand it and be able to comment.
For what I see so far what you mean is that in brightfield we see transmission and with the FTIR device we see reflection.
Thanks for your informed reply. I bet you have a physics degree. Or PhD!
Hello Ramon,
I think in order to understand, what's going on with the "green stuff" in your pictures, we have to sort out the different lighting techniques, involved.
In this picture:
IMG_20260523_175404.jpg
you use your device with the plate illuminated from the sides with LED's
The slide was mounted on the plate via immersion oil. No further lightening.
Right?
In the first picture:
IMG_20260523_175440.jpg
you Illuminaten from the bottom via the trans illumination of your scope, Thus to speak the lightening in the bottom of the scope and brightfield condensor.
Correct?
Greetings Holger
Zitat von: Spectrum in Heute um 18:06:05 NACHMITTAGSThe slide was mounted on the plate via immersion oil. No further lightening.
Right?
Hi Holger. Yes, the slide is mounted on top of the light guide (collector). Between them I placed a drop of immersion oil to make optical contact (index-matching). In the draw below you can observe the setup.
light path bio.jpg
We have eight light sources but for clarity only one is active in the draw.
Yes, no further lighting. All light sources are at the perimeter of the collector.
Zitat von: Spectrum in Heute um 18:06:05 NACHMITTAGSyou Illuminaten from the bottom via the trans illumination of your scope, Thus to speak the lightening in the bottom of the scope and brightfield condensor.
Correct?
YES. It is a simple compound microsocpe. Not a Kohler. Just a light source and a brightfield condensor. Below you can find it. In this instance we have the Dimomo device assembled on it but the light am using is the standard brightfield.Microscopio Brighfield.jpg
[quote author=Ramon link=msg=392976
Hi Holger. Yes, the slide is mounted on top of the light guide (collector). Between them I placed a drop of immersion oil to make optical contact (index-matching). In the draw below you can observe the setup.
light path bio.jpg
We have eight light sources but for clarity only one is active in the draw.
Yes, no further lighting. All light sources are at the perimeter of the collector.
[/quote]
Ok,
This resembles mostly some kind of darkfield illumination.
Most of the light raus are hitting the specimen from a flat angle from all around the sides.
Few of them reach the objektives entrance pupil, I would guess. (They are scattered more or less randomly at total reflection Level of the "plate", till they reach the oiled part.
But why does the fern show green colour?
Hm, the sporangium of ferns show strong fluorescence...
Especially when there is some UV or blue light present.
All "white" LED's have a very prominent content of blue light.
So, my guess...:
There is apart of the darkfield also some fluorescence happening. That, so my guess, is what causes the "green stuff".
Perhaps (no bet on that!) the green fluorescence is also amplified by some effect also used in a technique called "TIRf".
In TIRF illumination you use total reflection in order to illuminate only a narrow layer of the probe with the exiting wavelengh for fluorescence.
Look here:https://en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope
But it's very questionable if this is happening here.
Why?
Because common darkfield with the proper exitation wavelengh is causing fluo as well...
The frustrated total internainternal reflection is an effekt, that similar with TIRF but with white light and with no fluorescence effects. It also only occurs very close to the layer facing the illuminated surface. And I mean very close.
It is used for fingerprint sensors or touchscreens.
Look here:
https://www.asc.ohio-state.edu/schumacher.60/class/570/notes/p036.pdf
The first (left) picture looks like some common brightfield image.
Greetings Holger