Thursday, January 28, 2016

that was easy

Considered how to build my "pico light" or collimation test light with a fiber optic strand and bright LED. Gathered the pieces needed.

A small box to hold—and contain—the emitter. I was imaging a jig to hold the fiber up to the emitter. Both carefully aligned to maximise the light sent into the flexible fiber. And that all boxed up to remove stray light.

The cheapo fiber optic lamp I had bought some time ago, both the top with the fan of strands, to harvest a strand or two, and the base with its emitter and battery compartment. How to cut the fibers so to ensure maximum transmission? Peaked inside the opening of the base. Wow. Big lens over the blue LED...

Power. Right, three AAs. I knew I had some in the radio bag. Loops. Leaks! Found three that looked OK and were still putting out over 1.3 volts each. Rummaged through the "adapters" box and finally came across one of the old multi-voltage units with a small plug that fit. Happily, already configured centre positive.

Grabbed some white LEDs from the parts bin and a coin battery to test. I thought I had picked up some super brights... There was one in a bag marked 9-11K 20mA. The right one? [ed: Yes. Tested the LED last April.] Hmmm. When it hit me. I'm going to a lot of trouble! Why not just use what's in front of me!

fiber optic light base inside box

With a pushpin, I made a small hole in the side of the box and passed one of the bright strands through. Done!

single fiber optic strand protruding outside box

It works! Wow. Now the outside of the box is shiny. And there's some light coming off the filament itself. So maybe I'll put some flat black material on the side of the box. And maybe I can sheath the optical fiber...

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