How to Get More Light Out of a Single Strand of Optical Fiber Attached to an LED




Posted in TechnologyLeds

Introduction: How to Get More Light Out of a Single Strand of Optical Fiber Attached to an LED

Very simple stuff, but it has to be seen to be understood.

Fiber optics works because the light moving along the fiber is kept inside it - it is reflected by the shininess of the surface of the fiber. This is "total internal reflection" - or at least for standard acrylic fiber, it's a high percentage of internal reflection, and that's good enough.

Therefore, to get light out of the fiber at any point other than the end, you will have to disturb that internal reflection. A very easy way to do this is to simply crimp the fiber beyond a certain angle, and as you can see, the remainder of the fiber will light up much more brightly.

You have to experiment with each thickness of fiber and each brightness of LED light source, but in general with a good high-bright LED you should be able to bend the fiber about 6 times without losing too much light out of the end of it.

I am using 0.75mm plain acrylic hobby fiber, and a strand of flashing color changing RGB high-bright LEDs.

This is the foundational concept that will allow you to make your own LED fiber projects - especially wearables. I've made cloaks and tutus that light up using this idea. Have fun!

PS if you need to figure out how to get your fiber attached to your LED, look here:



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    where did you buy your color changing led lights? I'm thinking of a project, but don't have any experience with this type of light. Your Instructable has inspired me :)

    1 reply

    I buy them loose in bulk from eBay, or you can get strands of multi-color changing ones from I believe.

    If you straighten it out again...will it lose the effect?
    Cos I want to find an LED replacement for EL wire...

    2 replies

    PS check this stuff out: - solid core that glows the whole way down. It is pricey though!

    Yes, if you straighten it out the effect will diminish. If you're looking to replace EL wire with LEDs you're going to have to work with dots instead of lines! Another thing you can do is to nick or roughen little patches of the fiber with sandpaper - that will also let light out, but if you do it too much you will lose the light further down the fiber, and you also run the risk of weakening the fiber so it breaks if you use it in a costume or something else where it will move around a lot. My recommendation is to get a project reel of fiber, like 75' or so, and just play around with it. Good luck :), but there are plenty of online suppliers. I buy it by the spool because I use a lot!

    Neat technique! I'm going to give it a try. Thanks for sharing.

    1 reply

    thank you so much :)