During the rapid design and development phase of all the geeky items we were creating for our wedding Sparkfun listed a new item on their website; a large fiber optic sheet. We bought one with the idea of integrating it into Mara’s dress but had to figure out a way to light it up. In the end we didn’t end up using it for the wedding, but I did come up with a way to create a powerful light source for it and I’m sharing it for others to use.
Fiber optic applications need light, a lot of light. More than a little 20mA LED can provide. In large installations, halogen or other powerful light sources are used to feed fiber optic installations. Usually these ‘light boxes’ are large, power hungry and produce a lot of heat.
A real fiber light source
Since we were trying to use the sheet on a wedding dress the light box had to be compact and light weight. I decided to try using a High Power Luxeon LED to feed the sheet.
Better than a 20mA LED
A quick test holding the LED to the fiber connector proved it could work, but alignment is key. I would need to build something to hold the fiber connector in a sweet spot just above the LED. And I would have to deal with the heat the LED produces. So I sat down to my CAD program and came up with this:
Light box design
The design comes in two parts. The top piece holds the LED and fiber connector, the bottom holds a really tiny fan available from Digi-key for $15. The idea is the fan draws air through holes in the top piece, through the empty mounting holes on the LED board, across the back of the LED board and out through the bottom piece. I fired up the 3D printer and had my prototype printed in less than an hour.
Parts to assemble (All images click to enlarge)
Fan in bottom piece
LED in top piece
Snap bottom on top and line up wire slot
Connected to fiber sheet
The fiber connector fits loosely in the top piece, this allows in/out adjustment to position the connector at the right height off the LED for even light distribution. Once found, I taped the connector in place but gluing would be better for long term applications.
Now it’s time to see it in action.
In a dark room with no flash
With camera flash
Up close, no flash
A nice bonus is the fan is 3V, so with a white LED you could power the fan in parallel with the LED since it has a 3V forward voltage. This would make wiring easier and the whole unit could run off a Sparkfun LED driver board. And that’s it! We couldn’t find a nice way to integrate this into Mara’s wedding dress but maybe someone else may find a use for it! I’ve let this light box run at 600mA (~2W) overnight with no failures.
All design files available for download HERE on Thingiverse
If you don’t have access to a 3D printer email me at the address on the bottom of the page. I’m willing to print you a copy for the cost of shipping and a few bucks to cover plastic.
Some image are CC BY-NC-SA 3.0 from Sparkfun.com
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