Using through hole 5mm LED to illuminate fiber optic

[bamix]

Hello,

I'm an EE intern and for the summer one of my projects is to figure out how to make side emitting plastic fiber optics glow uniformly and brightly under room lighting.

So far, I've tried the most intense LED with smallest viewing angle I can find on Digikey and other suggestions I found online (such as boring a hole in epoxy casing and bending the fiber). These solutions have yielded good results when lights are turned off, but still has plenty of room for improvement for operating under room lighting. The most reasonable next step would be to try lenses (TIR, convex, ball, etc.), which I've started to research, but I wanted to get the opinions of you guys.

My team is only concerned with being able to make the fiber glow brightly under ambient lighting for up to 2 feet, there's no requirement for data transmission. Any suggestions on how to accomplish this?

 

[zeusfaber]

I'm making this up as I go along, but how about drilling a small hole in the end of the LED's plastic housing and glueing the end of the fibre into the hole using a resin that's as good a match as possible in terms of optical density to the material of the fibre and the housing (maybe polyester casting resin would be worth trying). The idea being to couple the light into the fibre without suffering the losses you get every time you cross a huge change in impedance.

A.

 

[3DDave]

Look at how many lumens that are expected. Now imagine that all those lumens are originating on a piece of silicon less than 1mm square. I suspect that what's being asked for cannot be done without a brief flash as the LED ignites or vaporizes.

Even EL wire, which produces illumination over its entire surface, can't be said to be "bright" under ambient (whatever lever that is) lighting.

 

[itsmoked]

You can't use LEDs. Their photon output is spread over too large an area. The numerical aperture is kicking your butt. Fibers essentially need a smaller light source than the fiber core. Another way to say it is that any of your source's area that exceeds the core's face area flat doesn't get injected into the fiber.

You need to go for a laser

A much lower power laser can inject a much higher amount of radiation into a fiber as compared to a LED.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[bamix]

Thanks for the responses!

I forgot to mention that we are trying to stay away from using laser as much as possible.

 

[IRstuff]

I think most laser diodes will have the same divergence as LEDs, since they're basically constructed the same way:

https://www.laserdiodesource.com/fi...m_up_to_3W_c_mount_Focuslight-1389124842.pdf,

roughly 40 deg x 10 deg

However, laser diodes, because of their other properties, can be available with fiber-coupled outputs, so the collimation and optics required are already dealt with:

https://www.laserdiodesource.com/fi...0nm_Fiber_Coupled_Laser_Diodes-1532094763.pdf

TTFN (ta ta for now)
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[MacGyverS2000]

SE fiber is typically lit with high-intensity halogen bulbs due to the sheer amount of photons required to light up the fiber appreciably during the day. At night you can get away with a several-Watt LED. If you must go with LEDs as the light source, you really need a light engine, not a single LED, and all of the focusing optics that go along with the engines.

Is your boss helping lead you in the right direction(s)?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Compositepro]

Are there any ideas you can use here:

https://www.google.com/search?q=led...KHVX0DXkQsAR6BAgFEAE&biw=1366&bih=604#imgrc=_

 

[bamix]

@MacGyverS2000

I've come across light engines but haven't been able to find anything that explains how to design one. Do you have anything on how to design one?

My boss is one of the senior principal engineers and the only EE but doesn't have a background in optics. So he's reaching out to other companies more specialized in the field and waiting to hear back, but most of the research on our team I do myself since he doesn't know what to do either.

 

[MacGyverS2000]

Light engine is just a generic term for a slew of LEDs on a single board, often with integrated electronics to control light output over temp ranges, etc. In essence, you need a LOT more light than you'll ever get from a single LED.

Dan - Owner

http://www.Hi-TecDesigns.com