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I just built a 17 LED substage strobable illuminator. The light is bright enough but the diffuser (blue?) that came with the scope (glass hemisphere) dims the light severely and with/without the diffuser the LEDs act like miniature spotlights. The LEDs are arranged in a rectalinear pattern with yellow, 2 green, and white comprised of 4 LEDs each and 2 and 3 for 2 wavelengths of red.
The LEDs are positioned with their bottoms about 7mm above the circuit board and (ugh!) point to point wired on the bottom of the circuit board.
I am looking for a means to 1) diffuse the light without reducing the lumens through it to much and 2) reducing or eliminating the bright spot effect. Could I have mounted the LEDs too close to the diffuser?
I can remove the existing diffuser. I have considered using Plexiglas and paint it with some kind of "craft" glaze but am looking for alternatives to consider for the diffuser.
Also, I have some parts to add a 9cm rotating stage which would be elevated 2cm above the fixed stage to clear the mechanical stage. I know most rotating stages are 16cm. Since point counting can be done on the fixed stage, I haven't thought of a limitation caused by the smaller diameter. Suggestions here would be welcomed.

Hi geo1,

Your led design sounds interesting, I've thinking about playing with led illumination, I'm good on electronics but not that good on optics.

What I suppose is that the total flow of light that you get out of de diffuser is the same that enters it (with some little lost, of course), the difference is that when it comes directly from the leds it's more directed in a cone, and when it crosses the light diffuser the rays of light flow in all directions: even out of the condenser.

Probably putting more leds, and further from the diffuser you will get out of the spotlight's effect.

It's a really interesting experiment, could you please post some pictures of your arrangemente? (you can use the button when writing your reply to the post)

Grettings, and have a happy new year.

Here are the pics of the LED strobe circuit, LED matrix, LEDs on a prototyping board, point to point wiring (UGH!) of the LEDs, External view of control box, Internal view of control box, Microscope interior w/ mounted LEDs, and Microscope's exterior w/ control switch/power.
From the LED matrix and wiring it should be obvious that one would be better served to mount the LEDs on a dual clad copper board which would have the lower surface blocked out for individual anodes and the entire upper surface used for the cathodes (or vice versa). After suffering the indignities of pt.-2-pt. wiring this would be a far better solution.

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Woow, it's a really nice design, I'll have to try it when I find some spare time.

Did you take some pictures we could see with this light arrangement? :-)

Thanks for sharing!

I had a moment to take some pics of a blood drop BUT I have not had time to do a proper configuration of the digitizer adapter so the pics are not centered like I'd like.
When taking the pics I discovered I was not getting the observed color in the pics so I am presenting only a couple which resolved close. I also checked my memory of using darkfield illumination and yes it is very effective, especially at 660nm.
The pics here are of the white light, green (500nm), and red (660nm). Note they are all at the same focal length (100x) without refocusing (parfocal). The red is receiving too much light and washes out. These were taken while resting the webcam on the adapter so were kind of hand held. I also warn that at 40x the LEDs create definite focal centers depending on their their position in the matrix. This might (?) be modified if placed further away from the scopes diffuser or if the ends of the LEDs are cut off leaving a flat end.
They're really poor but wanted to give you an idea of the performance and capability of the gaget before you went off and built one, and what a bad photographer I am.
Sorry my time compressing on me so that's my excuse. Enjoy.

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I know this thread is a year old, but maybe the OP's still around? If not, maybe someone else can clarify, as I have a simple question. PWM is certainly the obvious technique for dimming LEDs, but why make the frequency adjustable? Ie, what reason for being able to strobe the light? This seems like a great project as the LEDs won't heat up nearly as much as an incandescent lamp, so samples don't get cooked. I'd like to try to build it. Just wondering why the strobing.

Thanks,
Adam O.

Hi AdamO :-), is nice to read you, finally the forum is getting some more movement, that's good :-)

I'm not totally sure, but I think the frequency of the PWM is adjustable so you can use it not only as dimming but as an stroboscopic light.

With an stroboscopic light you can "freeze" fast moving specimens like ciliates if you have a camera.

Probaby, for that exact purpose a flash sync'd to your camera would be the best option, but with this cheap setup, and some patience you could get almost the same effect.

Geo1, am I right? :-)

Hey Ajo,

yeah it's a great forum! I don't know why it's so quiet. Maybe not too many microscope people out there?...Anyhow I'm really glad to join you guys and I hope I can contribute more than just pesky questions

That's interesting, about the fast moving ciliates. I will definitely like to give this "ghetto hack" a try! Ohhh so many projects, so little time.

-Adam O.

In response to why strobing-- 2 reasons a) to stop motion of live beasties e.g. the cilia and b) because I just bent that way --will someone answer the phone; there goes that tweaty bird again LOL

In response to your query elsewhere re: cameras and eyepieces-- the photos here were taken with an Encore web camera. Why Encore? It has a focus down to 5 mm. My method of mounting was to use PVC tubing and an end cap (which I cut to fit the slightly protruding focusing ring to keep it from slipping about). A piece of elastic medical strapping, a 1/8" tube and semi-elastic plastic medical tubing were used to lock the strapping in place against the PVC tube as it circled above and around the little spherical camera. I thought I had a picture of that (maybe not) with the rotating stage I did. Enjoy