Dichromatic Illumination?

[Nubee-70]

… I think, still, that the OPs project will still offer some interesting results …

Most definitely … I’m looking forward to seeing them
MichaelG.

Gee fellows, I don't know if there will be any interesting results.
I am a complete beginner in microscopy and a lot of the stuff you guys talk about go over my head.
All I know is that when things go over my head, it is a certainty that I lot I may say on the subject will be erroneous.

[Hobbyst46]

… I think, still, that the OPs project will still offer some interesting results …

Most definitely … I’m looking forward to seeing them
MichaelG.

Gee fellows, I don't know if there will be any interesting results.
I am a complete beginner in microscopy and a lot of the stuff you guys talk about go over my head.
All I know is that when things go over my head, it is a certainty that I lot I may say on the subject will be erroneous.

@Nubee-70 : IMHO, although the electronic project is probably a lot of fun to construct, the variety of useful wavelengths (namely, colors) for microscopy is quite limited - except, maybe, for excitation in fluorescence microscopy. For the latter, UV illumination can be useful, but precautions against eyesight damage are a must.
IR illumination - some crazy ideas come to mind, that require very sensitive IR sensors. I doubt whether ordinary cameras are such.

[Nubee-70]

[/quote]@Nubee-70 : IMHO, although the electronic project is probably a lot of fun to construct, the variety of useful wavelengths (namely, colors) for microscopy is quite limited - except, maybe, for excitation in fluorescence microscopy. For the latter, UV illumination can be useful, but precautions against eyesight damage are a must.
IR illumination - some crazy ideas come to mind, that require very sensitive IR sensors. I doubt whether ordinary cameras are such.
[/quote]
Thank you Hobbyst46 for your response. Yes, I am getting that message from others as well.
The above circuit (versions 1.3 and 1.4) includes IR and UV LEDs. Part of that circuit has a warning fashing LED to remind me to wear eye protection.

[jorymil]

I apologize for the somewhat dire tone of my OP. In terms of learning about microscope optics and lighting circuitry, this sounds like a really fun and worthwhile project. Even if you don't get exactly what you want, it sounds like a really worthwhile experience. Science is a lot of times about the unexpected.

If you're curious about light mixing, I highly recommend picking up a cheap spectroscope, such as https://www.amazon.com/Eisco-Labs-Econo ... YXRm&psc=1

and looking at a bunch of different things. This particular model also works well with a cell phone camera eyepiece adapter like

https://www.amazon.com/Telescope-Compat ... bXRm&psc=1

This really helps build intuition about different types of light.

Another fun mini-experiment is to hook up a voltmeter to differently colored LEDs and take note of how voltage relates to color. Basic single-color LEDs are best for this; once you start delving into COB and other integrated-circuit-type sources, there's a lot more going on behind the scenes.

John

[Nubee-70]

I apologize for the somewhat dire tone of my OP. In terms of learning about microscope optics and lighting circuitry, this sounds like a really fun and worthwhile project. Even if you don't get exactly what you want, it sounds like a really worthwhile experience. Science is a lot of times about the unexpected.

If you're curious about light mixing, I highly recommend picking up a cheap spectroscope, such as https://www.amazon.com/Eisco-Labs-Econo ... YXRm&psc=1

and looking at a bunch of different things. This particular model also works well with a cell phone camera eyepiece adapter like

https://www.amazon.com/Telescope-Compat ... bXRm&psc=1

This really helps build intuition about different types of light.

Another fun mini-experiment is to hook up a voltmeter to differently colored LEDs and take note of how voltage relates to color. Basic single-color LEDs are best for this; once you start delving into COB and other integrated-circuit-type sources, there's a lot more going on behind the scenes.

John

Thanks John for info and the links. Lots to see and do there.

[Nubee-70]

I have a light refraction (I think) problem that I hope anybody from the forum could guide me what to do, or just bear it.

[Nubee-70]

My solution to the above post is to drill a hole into the end and insert an optic fibre. Then light proof the whole thing, except for the end of the projected fibre.

[Hobbyst46]

A light guide does not "concentrate" light or "funnel" it or focus it, regardless of the geometry of the tip (square cut/frustum).
As mentioned, one can axially drill a 5mm LED, insert a 1mm-diameter (say) optical fiber into the bore, attach it with epoxy,
and cover the LED by means of a PVC shrink-tube to make the device act like a torch. A quartz fiber will transmit more light than an acrylic fiber.
Still, the emanating beam will not be focused. I tried this approach to illuminate a slide through the edge.

I guess that the dark ring in the previous photo is because of the discontinuity between the square end of the tip and the conical surface.

[Nubee-70]

A light guide does not "concentrate" light or "funnel" it or focus it, regardless of the geometry of the tip (square cut/frustum).
As mentioned, one can axially drill a 5mm LED, insert a 1mm-diameter (say) optical fiber into the bore, attach it with epoxy, and cover the LED by means of a PVC shrink-tube to
make the device act like a torch. A quartz fiber will transmit more light than an acrylic fiber. Still, the emanating beam will not be focused.
I tried this approach to illuminate a slide through the edge.

I guess that the dark ring in the previous photo is because of the discontinuity between the square end of the tip and the conical surface.

Thank you Hobbyst46 for info.
I will be using a 3mm dia end glow optic fibre (for starters). I have smaller diametres too.
Yes, I also was thinking about using black heatshrink.

[MichaelG.]

My solution to the above post is to drill a hole into the end and insert an optic fibre. Then light proof the whole thing, except for the end of the projected fibre.

.

I regret to say, you are likely to be disappointed … Fibre Optics have an ‘exit angle’

MichaelG.
.

Here are some reasonably self-explanatory shots of a small diameter bundle that I did a few years back:
… an individual fibre behaves the same way
.

IMG_5271.jpeg (131.57 KiB) Viewed 22745 times

.

IMG_5272.jpeg (146.01 KiB) Viewed 22745 times

.

IMG_5274.jpeg (123.3 KiB) Viewed 22745 times

.

[Chas]

'Why the flare out' .. 'why the black ring' ?
My guess; the light that is entering the cone and going less than the critical angle will exit the cone and other light (heading straighter) will bounce down the inside of the cone (?)
I think that the cone ought to concentrate light.

Conrad Beck in 'The Microscope A simple Handbook' (1921) mentions crossed illumination using Red and Blue light...... ' difficult structure may be more easily interpreted' (page 39).

Beck 2 colour illumination.jpg (94.06 KiB) Viewed 22706 times

[Hobbyst46]

Copied from the site of a firm named Synopsys. It shows the light losses when the tip is tapered to produce a narrower end.
They state that losses are substantial.

light guide.jpg (4.73 KiB) Viewed 22700 times

[Nubee-70]

My solution to the above post is to drill a hole into the end and insert an optic fibre. Then light proof the whole thing, except for the end of the projected fibre.

I regret to say, you are likely to be disappointed … Fibre Optics have an ‘exit angle’

MichaelG.

Here are some reasonably self-explanatory shots of a small diameter bundle that I did a few years back:
… an individual fibre behaves the same way...

Thanks for heads-up, and the photos.
To me, what you have shown with the green LED looks great to me... but disappointing for you. Because of this it is obvious that I don't know much about microscopy, and have lots to learn.

[Nubee-70]

'Why the flare out' .. 'why the black ring' ?
My guess; the light that is entering the cone and going less than the critical angle will exit the cone and other light (heading straighter) will bounce down the inside of the cone (?)
I think that the cone ought to concentrate light.

Conrad Beck in 'The Microscope A simple Handbook' (1921) mentions crossed illumination using Red and Blue light...... ' difficult structure may be more easily interpreted' (page 39).


Beck 2 colour illumination.jpg

Very interesting. I guess, optics is a science on its own...which I know very little about. Something else my me to learn.

Thanks. This helps to confirm what someone said earlier.
It sure is about wavelengths. It seems that the best way of getting those coloured wavelengths is not by mixing wavelengths but from white light via filtration.

[Nubee-70]

Copied from the site of a firm named Synopsys. It shows the light losses when the tip is tapered to produce a narrower end.
They state that losses are substantial.
light guide.jpg

Damn.
Well, I got the LEDs and in combination will take up a larger than required diameter of light beam. So I have no joice but to produce a narrower end, and live with the losses.
Thanks for warning me, and preparing me for why it won't work without losses.

[MichaelG.]

Thanks for heads-up, and the photos.
To me, what you have shown with the green LED looks great to me... but disappointing for you. Because of this it is obvious that I don't know much about microscopy, and have lots to learn.

.
Fear Not !!

We all have lot to learn … that’s one of the beauties of this forum … we can share what little we each have learned.

May I suggest you take a look at Ball Lenses …

MichaelG.
.
.
P.S. __ just for completeness, my Illumination source was a green laser pointer

[Nubee-70]

Thanks for heads-up, and the photos.
To me, what you have shown with the green LED looks great to me... but disappointing for you. Because of this it is obvious that I don't know much about microscopy, and have lots to learn.

.
Fear Not !!

We all have lot to learn … that’s one of the beauties of this forum … we can share what little we each have learned.

May I suggest you take a look at Ball Lenses …

MichaelG.
.
.
P.S. __ just for completeness, my Illumination source was a green laser pointer

Cool. Thank you Michael.
I checked the ball lenses and one of the manfacturers can make a 5mm dia glass ball with a max focal length of 4mm. I think that crowds it a bit with an obecjective lens. But I get the idea. A more flatter lens ought to work better.

[Nubee-70]

WELL! As others have already mentioned _ without light scattering within a medium the mixing of two coloured LEDs does not work well.

[jorymil]

But did you have fun trying it out? There's almost always going to be someone who's done something before you, but the knowledge you gain for yourself is still worth it. I think all of us here love the giddy feeling of discovery.

Not sure what your math/science background is, but you might want to check out an optics course or two on Coursera: they're free, and some let you take them for credit, too. It sounds right up your alley, and learning about the basic physics of refraction, diffraction, lenses, and light fibers will really help you in your designs. Stuff like total internal reflection, refractive index, etc. is very germane to what you're doing. You get the basics of this stuff in a second-semester physics class, too, depending on your inclination.

[Nubee-70]

But did you have fun trying it out? There's almost always going to be someone who's done something before you, but the knowledge you gain for yourself is still worth it. I think all of us here love the giddy feeling of discovery.

Not sure what your math/science background is, but you might want to check out an optics course or two on Coursera: they're free, and some let you take them for credit, too. It sounds right up your alley, and learning about the basic physics of refraction, diffraction, lenses, and light fibers will really help you in your designs. Stuff like total internal reflection, refractive index, etc. is very germane to what you're doing. You get the basics of this stuff in a second-semester physics class, too, depending on your inclination.

Thank you jorymil for your support, and help in this matter of optics.

[Nubee-70]

Correction to PWM circuit.
Sorry about that.

My circuit drawing (version 1.4) had a fault which stopped the circuit from performing properly. Pins 12 and 5 of IC2 needed a pull-down resistor (R*) for a '0' gate reading. I used a 1k resistor.

[charlie g]

Great thread, Nubee..thank you and group. I often wonder what most closely simulates the natural ambient illumination regime of observed living protists and meiofauna.

Are not sand particle interstices inhabiting organisms exposed to a totally different insolation reality than the 'blast of microscope stage illumination' we utilize in visual observations, or in image captures?

Same vast disparity between our microscope stage illumination blasts of organisms thriving within pond sediments, or those thriving in thick vegetation matts, etc., etc. natural habitats.

So is not the only reasons for 'Dichomatic Illumination' (transmitted illumination blast, or episcopic illumination blasts) ...is not the reason to explore possible better contrast methods of target organisms...or pleasing to our eye

illumination schemes?

Action spectra of different organisms in their habitats yield conditions in which said organisms thrive...my sense is this variety of illumination treatments have already been worked out for many microhabitats, during seasons cycles.

I mention this in ' Dichromatic Illumination' thread, as for years I noted irritability and behavior changes in protist and meiofauna I observe..when I switch from one transmitted phase objective, to a different magnification phase objective.


One level of transmitted illumination seems to keep ' all is well with the world' ..than alteration of illumination intensity literally irriates the observed organism to actively leave the illuminated area of the wetmount slide.

When my son was four years of age, I'd carry him about our garden on warm summer nights, my boy would hold the torch. We were on safari for night active spiders, bugs..always..always the huge earthworms would retreat into their tunnels abruptly when the light beam touched them.

I purchased a "Night Hawk" night vision low cost optical viewer to use with vertical port on trinocular microscopes...alas I never applied this optic. My thoughts were/ are...do my neighbor protists and meiofauna behave differently in the low light environment ...than their behavior in the unnatural light blast illumination they are subjected to in our visual/ image capture microscopy?

I'm thinking, Nubee, why don't you explore behavior changes in live protists/ meiofauna with your 'Dichromatic Illumination ' treatments...after all..all our illumination schemes are vastly different from habitats these protists/ meiofauna naturally thrive in.

thanks for your thread, charlie g

[Nubee-70]

Great thread, Nubee..thank you and group. I often wonder what most closely simulates the natural ambient illumination regime of observed living protists and meiofauna.

Are not sand particle interstices inhabiting organisms exposed to a totally different insolation reality than the 'blast of microscope stage illumination' we utilize in visual observations, or in image captures?

Same vast disparity between our microscope stage illumination blasts of organisms thriving within pond sediments, or those thriving in thick vegetation matts, etc., etc. natural habitats.

So is not the only reasons for 'Dichomatic Illumination' (transmitted illumination blast, or episcopic illumination blasts) ...is not the reason to explore possible better contrast methods of target organisms...or pleasing to our eye

illumination schemes?

Action spectra of different organisms in their habitats yield conditions in which said organisms thrive...my sense is this variety of illumination treatments have already been worked out for many microhabitats, during seasons cycles.

I mention this in ' Dichromatic Illumination' thread, as for years I noted irritability and behavior changes in protist and meiofauna I observe..when I switch from one transmitted phase objective, to a different magnification phase objective.


One level of transmitted illumination seems to keep ' all is well with the world' ..than alteration of illumination intensity literally irriates the observed organism to actively leave the illuminated area of the wetmount slide.

When my son was four years of age, I'd carry him about our garden on warm summer nights, my boy would hold the torch. We were on safari for night active spiders, bugs..always..always the huge earthworms would retreat into their tunnels abruptly when the light beam touched them.

I purchased a "Night Hawk" night vision low cost optical viewer to use with vertical port on trinocular microscopes...alas I never applied this optic. My thoughts were/ are...do my neighbor protists and meiofauna behave differently in the low light environment ...than their behavior in the unnatural light blast illumination they are subjected to in our visual/ image capture microscopy?

I'm thinking, Nubee, why don't you explore behavior changes in live protists/ meiofauna with your 'Dichromatic Illumination ' treatments...after all..all our illumination schemes are vastly different from habitats these protists/ meiofauna naturally thrive in.

thanks for your thread, charlie g

Thank you charlie g for your indepth response to your experiences with illumination treatments. Very inspiring and interesting.
I am still waiting for some parts to my project, and hopefully improving my design as well, but we shall see if this is so. Will be reporting again shortly (I hope).

[FredH]

Hi Nubee,

What is the function of the 4001 nor gates in your circuit? It looks like IC2a, IC2b, IC3a just invert the 555 output to VR4; IC2c, IC3b just send the (uninverted) 555 output to VR2. Why not just use a single nor-gate inverter to VR4, and tie the 555 output directly to VR2? Or better, wire IC2a, 2b, 2c, 2d inputs and outputs parallel to give more drive capability -- if the 4001 is some version of CD4001, it probably can drive no more than 8.8 mA, while the 555 can drive about 200 mA. But maybe I'm misunderstanding your intention.

Also, what is the point of connecting both switches in the "off" position to resistor RL? Seems like this just wastes a little current, while if both switches are "off", IC3a and IC3b outputs are fighting each other. Why not leave the "off" position switch terminals unconnected?

Also, I think your warning flasher circuit needs a resistor to the VISbar switch terminal or it won't blink -- it will just light up when Q1 reaches the reverse breakdown voltage, and stay lit up, without blinking.

[Nubee-70]

Hi Nubee,

What is the function of the 4001 nor gates in your circuit? It looks like IC2a, IC2b, IC3a just invert the 555 output to VR4; IC2c, IC3b just send the (uninverted) 555 output to VR2. Why not just use a single nor-gate inverter to VR4, and tie the 555 output directly to VR2? Or better, wire IC2a, 2b, 2c, 2d inputs and outputs parallel to give more drive capability -- if the 4001 is some version of CD4001, it probably can drive no more than 8.8 mA, while the 555 can drive about 200 mA. But maybe I'm misunderstanding your intention.

Also, what is the point of connecting both switches in the "off" position to resistor RL? Seems like this just wastes a little current, while if both switches are "off", IC3a and IC3b outputs are fighting each other. Why not leave the "off" position switch terminals unconnected?

Also, I think your warning flasher circuit needs a resistor to the VISbar switch terminal or it won't blink -- it will just light up when Q1 reaches the reverse breakdown voltage, and stay lit up, without blinking.

Yes FredH you are correct on all accounts. Thank you for pointing those bits out. I failed to think it out and keep it simple. It's been over 36 years since I've done this sort of stuff. Just lazy on my part. I built the cct 36 years ago and it had another signal, lower pulse rate, coming into IC2c pin 12 which carried the PWM frequency. But that is no longer needed and with your clarity has now reduced to one 4001 IC.

I put the load resistor on the OFF position because for some reason I did not want the gate output to be directly connected to earth when the VR = 0. But you are correct about just let the OFF be an open cct.

I forgot to show the resistor in the flashing circuit. Using a BC547 transistor, the needed resistor turns out well 11k.

Thanks again for helping me out.

[Nubee-70]

Thanks to FredH I have been able to simplify the circuit, now being (version 1.5)



I have tested this circuit on a test board, and it works fine. The question is, will I be able to come up with a simple light projecting solution.

[GerryR]

You might want to look at my holder in the following thread to get some ideas of what to do. By the way, a very nice project and well thought out!! I wish I had put a little mre thought into mine.
viewtopic.php?f=28&t=19369&p=141099#p141099

[Nubee-70]

You might want to look at my holder in the following thread to get some ideas of what to do. By the way, a very nice project and well thought out!! I wish I had put a little mre thought into mine.
viewtopic.php?f=28&t=19369&p=141099#p141099

Cool. I am glad to see your setup. It has given me further thoughts about what I am trying to do...thanks for your input GerryR.
Strange how we had similar ideas around the same time (synchronicity).

Later.....
This thread has certainly been, for me, a process of elimination, as opposed to illumination.
So my next step is to valuate the difference between DC vs PWM as a way to mix colours. Something tells me that there will be a difference dependant on method of light projection.
Anyway, I will simple put in a switch to make the comparisons.

[GerryR]

You might want to look at my holder in the following thread to get some ideas of what to do. By the way, a very nice project and well thought out!! I wish I had put a little mre thought into mine.
viewtopic.php?f=28&t=19369&p=141099#p141099

Cool. I am glad to see your setup. It has given me further thoughts about what I am trying to do...thanks for your input GerryR.
Strange how we had similar ideas around the same time (synchronicity).

Later.....
This thread has certainly been, for me, a process of elimination, as opposed to illumination.
So my next step is to valuate the difference between DC vs PWM as a way to mix colours. Something tells me that there will be a difference dependant on method of light projection.
Anyway, I will simple put in a switch to make the comparisons.

They say "great minds work together"...who are we to argue?? On a more serious note, unless you are going to photograph your specimens, I don't think DC is going to make much difference. If photographing, then you have to be aware of the PWM frequency vs camera shutter speed. I made mine so the pulses to all 4 leds are synched and you can vary the intensity to each led individually, and you can shut off each led if you have a mind to. The shortcoming to the way I did the "pwm" is I am limited to 10 uS as the smallest on time per led at approx. 100 hz rate (just the rate I chose) so I added a switch to each led to shut it off completely. Its not a perfect system, but it was a fun project.

[Nubee-70]

They say "great minds work together"...who are we to argue?? On a more serious note, unless you are going to photograph your specimens, I don't think DC is going to make much difference. If photographing, then you have to be aware of the PWM frequency vs camera shutter speed. I made mine so the pulses to all 4 leds are synched and you can vary the intensity to each led individually, and you can shut off each led if you have a mind to. The shortcoming to the way I did the "pwm" is I am limited to 10 uS as the smallest on time per led at approx. 100 hz rate (just the rate I chose) so I added a switch to each led to shut it off completely. Its not a perfect system, but it was a fun project.

Okay, thanks for that information. I am looking forward to seeing what photos and videos I take.
It is all part of experimentation is it not. So far, on this project, nearly everything has blown up in my face.