FIBER OPTICS?

[olav]

I've been using this small minimaglite fiber optics in my work. It fits perfectly to my Led lenser David 19.
As I'm getting older I find that this combination isn't enough for me - as it usually is with flashlights.
I wonder if you have some recommendations for getting more lumens through tiny holes ? ? ?
:help:

 

[DM51]

Cross-posted - closed.

Edit: correction - the index showed a 2nd thread in another section, which was not in fact there. My apologies, olav - thread re-opened.

 

[saabluster]

I've been using this small minimaglite fiber optics in my work. It fits perfectly to my Led lenser David 19.
As I'm getting older I find that this combination isn't enough for me - as it usually is with flashlights.
I wonder if you have some recommendations for getting more lumens through tiny holes ? ? ?
:help:

For this to work you will need to make the light dedicated for this purpose only. You will need to take out the optic and pull the fiber optic through the rubber piece that holds it so that you can butt the fiber right up to the face of the LED. You will get significantly more light out that way.

 

[jrmcferren]

The problem with fiber optics, even with communication grade fiber, you lose a lot of power at visible wavelenghts. I am taking a fiber optics course right now. As the wavelength increases the further out of tune the fiber is and the more light is lost. I don't know the details of plastic fiber, but I do know that the losses are HORRIBLE at communications wavelengths (the shortest being 850 nm), so the losses at visible wavelengths would be even worse.

 

[olav]

Thank you for your advices. I took some "before - after" pics as I moved the fiber to the lens of my Ledlenser.

I suppose if I want to get even more lumens I have to get a flashlight with proper led and thicker endglowing fiber ?

What kind of endglowing fiber could I use, if it should be a bit flexible and approx. some 6 mm of diameter ?

 

[saabluster]

Thank you for your advices. I took some "before - after" pics as I moved the fiber to the lens of my Ledlenser.

I suppose if I want to get even more lumens I have to get a flashlight with proper led and thicker endglowing fiber ?

What kind of endglowing fiber could I use, if it should be a bit flexible and approx. some 6 mm of diameter ?

No problem:thumbsup: You will not find a 6mm fiber that can still flex. At least I don't know of one.

 

[olav]

How about PMMA fiber (plastic) It can be used at temperature -40 ...+80 celsius. Could it be attached to led ?

http://www.swicofil.com/products/278polymethylmethacrylate.html

You can find PMMA fiber for example in 6 mm and I suppose it will flex a bit ?

 

[saabluster]

How about PMMA fiber (plastic) It can be used at temperature -40 ...+80 celsius. Could it be attached to led ?

http://www.swicofil.com/products/278polymethylmethacrylate.html

You can find PMMA fiber for example in 6 mm and I suppose it will flex a bit ?

At 6mm it really will not bend appreciably. Maybe if if was a combination of a bunch of smaller fibers but not one big one.

 

[olav]

Got the new PMMA "fibers"

From the left 6mm, 3mm, 2,5mm and old fiber for Minimaglite

I attached the 6mm PMMA to Energizer keychain with 5mm led (top). Below Ledlenser with standard fiber and next UK with standard fiber.

The 6mm PMMA "fiber" was quite flexible and easy to work with. You can easily even bore the fiber to fit better to the head of the 5mm led. You can also use sharp knife to shape the 6mm PMMA fiber. It's quite soft. The thinner ones were much harder and you have to use force to cut them.

BEAMSHOTS ?

Well.. I will add beamshots when I get a proper ledlight and after I find a good adapter for the fibers ? Maybe I should try to attach lens to the 6mm. (DX sku 13905)

 

[saabluster]

The 6mm PMMA "fiber" was quite flexible and easy to work with. You can easily even bore the fiber to fit better to the head of the 5mm led. You can also use sharp knife to shape the 6mm PMMA fiber. It's quite soft. The thinner ones were much harder and you have to use force to cut them.

Nice work. I am glad you came back to update us. The 6mm PMMA that I have is not flexible. I wonder what they put in it to make it that flexible.

 

[brucec]

The problem with fiber optics, even with communication grade fiber, you lose a lot of power at visible wavelenghts. I am taking a fiber optics course right now. As the wavelength increases the further out of tune the fiber is and the more light is lost. I don't know the details of plastic fiber, but I do know that the losses are HORRIBLE at communications wavelengths (the shortest being 850 nm), so the losses at visible wavelengths would be even worse.

Not accurate, but you are not done with the course yet... Insertion loss into optical fiber or an optical fiber bundle is the primary culprit for lack of lumens, especially at these short lengths. To get light coupled into optical fiber, one must match the NA. Optical fiber can only accept and guide light within a certain cone, whatever falls out of the cone will not be guided and simply escape out the sides instead of the front. Simply butting the end of a fiber up to the light source may not give any improvement at all. Using a lens to focus the light at the correct angle of acceptance will give you the best coupling efficiency. I don't know if this is an option or not, but most optical fiber systems will use a coupling lens. There is also the issue of packing density in a fiber optic bundle, which will introduce ~10% loss right off the bat in a traditional bundle. Liquid light guides (flexible tubes filled with high index liquid) might be an option, but I forgot how transmissive they are.

 

[yellow]

quite more losses than these discussed be4 simply come from the fact, that the light emits "bad" for this.
click it on, and put it just a tiny bit away from the target: there will be an unlit middle (where the fiber is put) and a bright outer "ring".

To get really much light into the fiber, it has to sit as near to the led, as possible.

Try to disassemble the light, get the optic out and insert something of same size. Drill a hole in the middle and put the fiber trough. Insert fiber and fix it close to the led.
Now a great part of the emitted beam cone gets into the fiber, not just the direct spill as before.

 

[csshih]

hmm, where did you get the 6mm fiber?
looks fun.

 

[olav]

hmm, where did you get the 6mm fiber?
looks fun.

It's an Finnish webstore which provides home LED lightning items.

http://ledwood.valmiskauppa.fi/paastasaiteileva-kaapeli-6mm1metri-p-776.html

I suppose you will find in States several sites to get this kind of cabel?

Translation
6mm endglowing fiber protected with PVC plastic. For this cabel is recommend at least 50W halogen projector. Price 10 euro/meter. You can get it even in length of 30 meter.

As I mentioned earlier this 6mm cabel is bit softer to work with compered to the thinner ones.