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DIY Scienscope fiberoptic light
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Saul



Joined: 31 Jan 2011
Posts: 911
Location: Naperville, IL USA

PostPosted: Fri Sep 16, 2016 12:27 pm    Post subject: DIY Scienscope fiberoptic light Reply with quote

Parts used:
-Scienscope FO guide
-30W LED & driver
-LED reflector & collimator lens
-LED heatsink & fan
-some hardware, sorry for the too long screws Smile
-3D printed adapter & aluminum foil tape (inside reflector)

No vibrations from the fan at 20x. Did not try at 50x yet. Shelves are separated from the my setup, both standing on the carpet close to each other.

Any ideas and comments are welcome.



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Saul
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johan



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PostPosted: Fri Sep 16, 2016 1:07 pm    Post subject: Reply with quote

Just a thought, and I don't know if this is right or wrong but it might be worth looking at.

Vibrations could obviously be an issue with the fan, and actually I have a different project too that requires a fan and heatsink. But, I was tinkering with a PC utility called speedfan today, which measures PC fan speeds and temps. Anyhow, the long and the short of it was that I switched the fan off on my CPU fan... and actually the temperature didn't change AT ALL. As if the fan made no actual difference! So I don't know how you'd measure this, but see what the difference is with and without a fan running... which might help with vibration. I know for example that torches with LEDs don't have fans running yet they run LEDs too. Might be total rubbish, but on the other hand might help. Good luck =)
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Saul



Joined: 31 Jan 2011
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Location: Naperville, IL USA

PostPosted: Fri Sep 16, 2016 1:51 pm    Post subject: Reply with quote

johan wrote:
...Vibrations could obviously be an issue with the fan...


Thanks Johan !
Did not see (I made only one test yet) at 20x. In the new version of my controls I'll be switching on and off light so fan maybe will be not necessary for stacking itself, just for initial light preparation. Going to add some rubber gaskets just in case.
Heatsink was cold and 3D adapter was warm after 3 stacks ...
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Chris S.
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PostPosted: Fri Sep 16, 2016 11:07 pm    Post subject: Reply with quote

Interesting project, Saul! Very Happy Thanks for posting on it. I’d be interested in seeing more details of your reflector/collimator approach.

I use a set of three halogen illuminators with various FO light guides. I mount the illuminators on a shelf suspended by rope from the ceiling over my rig, for isolation of vibration from the fans. Have idly pondered adapting one of these illuminators to LED, and doing so with the others if successful. In my particular situation, LED wouldn’t provide any big wins, and might introduce metamerism. But I’m still tempted.

johan wrote:
But, I was tinkering with a PC utility called speedfan today, which measures PC fan speeds and temps. Anyhow, the long and the short of it was that I switched the fan off on my CPU fan... and actually the temperature didn't change AT ALL. As if the fan made no actual difference!

Johan, something here doesn’t seem right. I’ve built and maintained a rather large fleet of PCs, and on the rare occasions that a CPU fan stops working, the result is invariably dramatic—the computer behaves erratically and/or shuts down. So I’d say that the CPU fan is absolutely crucial.

I suspect that your motherboard may be overriding Speedfan to avoid damaging the CPU or motherboard components. If you’re tinkering with a desktop computer, you can look inside and see if the CPU fan is really shut off. My bet is that you’ll see that it’s still spinning. If not, your computer has other problems—for example, the CPU may have been throttled way down for its own protection, making your computer run much more slowly for any CPU-intensive tasks.

--Chris
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Pau
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Joined: 20 Jan 2010
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PostPosted: Sat Sep 17, 2016 2:38 am    Post subject: Reply with quote

Chris S. wrote:
I’d be interested in seeing more details of your reflector/collimator approach.

Me too!

Time ago I faced to a similar problem: electronic flash into fiber optics. It induced interesting discussions, although not a clear and easy solution. Finally I abandoned the project, I'm too lazy and too unskilled to experiment all options but the one that worked better in my dirty tests was the simpler one: just putting the light source as close as possible to the FO entrance. It will be really easy with a flat surface COB LED, but only would be really efficient if the LED size is similar to the FO entrance diameter
http://www.photomacrography.net/forum/viewtopic.php?p=92873
A previous thread on similar subject: http://photomacrography.net/forum/viewtopic.php?p=42872

At this FAQ post you can find some approaches , at the third group of links:
http://www.photomacrography.net/forum/viewtopic.php?p=161563
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johan



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PostPosted: Sat Sep 17, 2016 2:02 pm    Post subject: Reply with quote

Chris S. wrote:
Johan, something here doesn’t seem right. I’ve built and maintained a rather large fleet of PCs, and on the rare occasions that a CPU fan stops working, the result is invariably dramatic—the computer behaves erratically and/or shuts down. So I’d say that the CPU fan is absolutely crucial. I suspect that your motherboard may be overriding Speedfan to avoid damaging the CPU or motherboard components. If you’re tinkering with a desktop computer, you can look inside and see if the CPU fan is really shut off. My bet is that you’ll see that it’s still spinning. If not, your computer has other problems—for example, the CPU may have been throttled way down for its own protection, making your computer run much more slowly for any CPU-intensive tasks.


Yeah, I'm not so sold on Speedfan anymore as I've subsequently discovered that the information about the fan speed isn't entirely accurate. So sorry, this looks to have been a bum steer.
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Saul



Joined: 31 Jan 2011
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PostPosted: Sat Sep 17, 2016 9:48 pm    Post subject: Reply with quote

Pau wrote:
...
http://www.photomacrography.net/forum/viewtopic.php?p=92873
A previous thread on similar subject: http://photomacrography.net/forum/viewtopic.php?p=42872

At this FAQ post you can find some approaches , at the third group of links:
http://www.photomacrography.net/forum/viewtopic.php?p=161563


Thanks Pau !
Shocked Lots of reading and tons of useful information !
Before designing 3D part I made a quick test with the lens which came together with the LED - I was not able to concentrate the light beam to the size of the FO entrance. Please, correct me if I'm wrong - looks like that most feasible solution is to use microscope condenser ?
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Saul
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Pau
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PostPosted: Sun Sep 18, 2016 12:20 am    Post subject: Reply with quote

In fact I fear that microscope condensers aren't adequate (and in my few tests they weren't)

Quoting myself: I've tried microscope condensers but without much success, surely because its divergent light output
The more likely reason is because the entrance angle of light into the fiber optic, usually about 20-30deg. A microscope condenser is designed to take almost parallel light rays and concentrate and make them highly divergent while here we want almost the opposite: making highly diverging light concentrated and collimated (almost parallel)
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Saul



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PostPosted: Mon Sep 19, 2016 7:44 pm    Post subject: Reply with quote

Chris S. wrote:
..I mount the illuminators on a shelf suspended by rope from the ceiling over my rig, for isolation of vibration from the fans...


Shocked Did we see a photo of this marvelous design ? Smile

First stack with DIY FO guide at 20x, fan is on:
http://www.photomacrography.net/forum/viewtopic.php?p=197237#197237

My mistake, did not make any photos without fan at 20x. But made at 50x, objective is Nikon 50x 0.55, tube lens - Sigma Life-Size attachment, single shots

OFF


ON


Now question is :
-Is this really fan's vibrations influence
-Air stream from the fan
-One side of the guide was touching little bit a small piece of the toilet paper which I was using as partial diffuser

BTW, ordered 100 LED (stating up to 10 000 lm), 30w not enough for 50x ...I foresee problem with the heat, what I could use for the IR thermal filter ? What is used in the original halogen units ?
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Saul
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Chris S.
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PostPosted: Mon Sep 19, 2016 9:41 pm    Post subject: Reply with quote

Saul wrote:
Chris S. wrote:
..I mount the illuminators on a shelf suspended by rope from the ceiling over my rig, for isolation of vibration from the fans...


Shocked Did we see a photo of this marvelous design ? Smile

No. I've described it a few times, but haven't gotten around to documenting it any further. Not sure it's "marvelous"--it's just a shelf--but it's quite practical; I get very thorough isolation from the vibration of the fans, and the illuminators are located in a very convenient yet out of the way position. Since the illuminators are "floating" above my rig, the fiber optic light guides can quickly be placed anywhere around the subject. I have single, double, and quad-head light guides, so can put up to ten individual light sources on the subject. I probably don't need that many, but the approach gives me similar lighting flexibility to what one would get with human models in a well-equipped studio.

Saul wrote:
Now question is :
-Is this really fan's vibrations influence
-Air stream from the fan
-One side of the guide was touching little bit a small piece of the toilet paper which I was using as partial diffuser

I can't say for sure in your situation, but will venture a guess based on my experience: It's vibration, not air flow.

When I first tried a halogen illuminator, I placed it on the slate pool table I use for studio macro, and the vibration was awful. I tried placing the illuminator on a sheet of bubble wrap, which helped not at all. Nor did two sheets of bubble wrap, nor three. I then tried a piece of closed cell foam, then a piece of open cell foam. Then a small, largely-deflated inner tube designed for a wheelbarrow. Of these, only the inner tube gave any meaningful improvement; it was not perfect, but I suspect I might have been able to tune it by adjusting the air pressure. But I didn't much like having the illuminator next to my macro rig, sitting on a floppy inner tube. The position was inconvenient--in the way, and forced me to route the light guides in annoying ways. And I didn't like the way the illuminator squirmed around on the floppy inner tube when I adjusted the intensity and iris knobs. So I took a piece of rope, tied it to the illuminator, and suspended it from the ceiling. Instant perfection! Very Happy Zero vibration, and great ease in routing the light guides. To be clear, this was not a series of carefully thought out tests, but a single evening of frustration followed by something working.

The next step was to buy a piece of wood big enough to hold three illuminators, put some eyebolts into the four corners of the wood and into the ceiling joists, and tie in strands of rope to suspend the shelf. Importantly, I also tied the illuminators onto the shelf, to prevent user error from causing an illuminator from crashing down on my macro rig.

Anyway, since my devil was fan vibration, and the air from the fan has caused me zero grief, I suspect vibration to be your devil, as well.

As to whether your light guide's touching the toilet paper is the culprit, I'd bet not, toilet paper being a poor conductor of mechanical energy. I don't find my light guides to be effective conductors of mechanical energy, either--but none of mine are "compliant," as yours seem to be.

Additionally, in your shoes, I'd be very tempted to throttle down the fans to where they move only fast enough to dissipate the heat. This, of course, can be done by adding a series resistor--a trimpot might be ideal. But you've likely considered this.

Saul wrote:
I foresee problem with the heat, what I could use for the IR thermal filter ? What is used in the original halogen units ?

Fostec's literature describes an "IR interference filter for cool illumination." Looking at two of my units just now, it is a one-inch square of glass, about 1/8 inch thick. Since Fostec specifies "interference" for this filter, I assume it is dichroic, passing visible light and reflecting (rather than absorbing) infrared wavelengths.

One possible source of such filters is Edmund Optics IR cutoff filters. Before buying, I'd suggest asking EO's customer support engineers if these models reflect or absorb IR light. The former would be the better choice, as the IR would be reflected toward your fan, rather than being heating up the filter. I'm a bit surprised that this is not specified in the listing.

Cheers,

--Chris
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Saul



Joined: 31 Jan 2011
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Location: Naperville, IL USA

PostPosted: Tue Sep 20, 2016 12:27 pm    Post subject: Reply with quote

Thanks Chris !

My guides are vibrating - I can easily feel it by touching by finger. I have some dampening material, have to try it. Regarding air stream - because it goes downwards and close to my setup , I still little bit concern, will make some temp covers and will test again.

I have never seen what is inside original FO illuminator (optical portion)



Just light bulb and IR cut off filter ? No aditional optics ? How many lumens it is generating (light bulb) ?
There are some numbers - 600-1000 lm from the FO output.
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Pau
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PostPosted: Tue Sep 20, 2016 12:55 pm    Post subject: Reply with quote

Quote:
Just light bulb and IR cut off filter ? No aditional optics ?


There are optics: the paraboloid(?) reflector of the EKE lamp is designed to concentrate the light at the FO entrance, although I think that a good part of the light is lost, at least in mine.

100W LED could be brutal!
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Saul



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PostPosted: Tue Sep 20, 2016 1:30 pm    Post subject: Reply with quote

Pau wrote:
...100W LED could be brutal!


I suspect the same Smile
I'm planing (if everything goes OK) to use
for setup not at the full power and during the stacking - switching on for couple seconds per step only.

http://www.photonics.com/EDU/Handbook.aspx?AID=25117 says that there is ~80 lm using 150W halogen bulb. Does not look
enough even for 20x ...
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Chris S.
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PostPosted: Tue Sep 20, 2016 10:04 pm    Post subject: Reply with quote

Saul, here is an altered copy of the technical diagram you posted, in which I’ve colored the IR filter blue for clarity. The non-colored tab on the left middle of the filter is a metal tab, protruding from the plate on left, that holds the filter in place. There are four such tabs, one on each edge of the square filter. The filter is additionally held in place by being sandwiched between the plate to its left and the plate to its right.



Pau wrote:
Quote:
Just light bulb and IR cut off filter ? No additional optics ?

There are optics: the paraboloid(?) reflector of the EKE lamp is designed to concentrate the light at the FO entrance. . . .

Pau is quite right. But as this is important, let me reinforce the point to make sure there is no misunderstanding. There are no lenses in front of the lamp, but the EKE lamp projects collimated light. An EKE lamp is a parabolic reflector with a halogen bulb at its focus point. Such a reflector sends the light rays out in parallel alignment along a reasonably narrow arc. This is why there is no need for collimating lenses.

Consequently, I suspect that if an LED were substituted, it would best be placed at the focus point of a parabolic reflector. Perhaps an EKE bulb could be scavenged for this?

For illustration, here is a GE EKE bulb available from Grainger.com. Many (most?) EKE lamps' reflectors are not composed of small plates, as this one is, but are smooth-sided. Also, many are far cheaper (about $8 USD, as opposed to this model's $40). Most do indeed specify about 80 lumens, while this one specifies 380 lumens. I wonder if this is a misprint, or if this is an extremely high-performance EKE lamp? Image from Grainger's listing.




Saul wrote:
. . . there is ~80 lm using 150W halogeng bulb. Does not looks enough even for 20x ...

In my experience, EKE bulbs cast plenty of light for 100x, even with cross-polarization, which wastes most of the light. Without X-pol, I have to dial back the intensity using my illuminators’ irises, in order to permit the 8-second exposures I prefer. Also, this is often with a quad head, which of course divides the light four ways. If you’re willing to use exposures in the realm of two seconds, I think you’ll be fine. This said, my experience may only apply if you can concentrate and collimate the light into the FO light guide with a parabolic reflector, or perhaps another approach.

BTW, I’m not at all sure that the light need be concentrated within the physical diameter of the FO light guide. I had a conversation about this with a leading researcher in fiber optics. He described optical fibers as having a numerical aperture/entrance cone. His sense was that my collimated light source need only fall within the optical fiber’s entrance cone—which would be larger than the diameter of the FO light guide—to be transmitted down the light guide.

Cheers,

--Chris


Last edited by Chris S. on Tue Sep 20, 2016 11:12 pm; edited 2 times in total
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g4lab



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PostPosted: Tue Sep 20, 2016 10:22 pm    Post subject: Reply with quote

The DDL lamps give you a few more lumens and a few degrees higher CCT.

I like the ones from Osram or Philips or Ushio. I don't use no name quartz halogen lamps if I can avoid it. The brand name ones don't cost that much if you buy them from a good supplier. I buy lots of things from Graingers but not spare lamps for my fo illuminators. They charge list price which is high.

The osram don't have the faceted reflector but I don't think that you will ever discern a difference after the light has gone through the fiber optic guide.

Many of the lamps used in FO illuminators were originally intended for eight mm movie projectors.
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