Five Buck Fiber Optics

I recently needed to use fiber optics for another project, and couldn't really find much diy info or a cheap way of coupling fiber to a laser diode. I was drawing some bits for a local guy to machine, and thought there's got to be an easier way than basically making a mini optics bench with lenses and clamps and stuff.

So I looked through my optics box and had a think and came up with this. Estimate over 90% gets focused to a .25mm spot on the end of a 1mm acrylic fiber. There is very little light splash from the inside of the housing. I used a standard 1 dollar toslink cable, cut with a razor and "polished" with a piece of glass at 170c.

I needed a violet laser delivered through fiber for a fluorescence application, and even with a PHR diode this delivers an intense output from the fiber with an angle of about 45 degrees. Don't get excited about turning the output into a beam though, unless a beam a foot wide is ok.



I took an Aixiz module removed the focus ring from the lens, and epoxied it to the open end of the rear housing exactly in the center. The hole in the closed end was drilled to suit the fiber (3.9mm in this case) with a 12 degree cone cutter, this grips the fiber tightly. The lens nut is screwed back onto a glass lens holder , then the assembly is screwed into the diode holder. Clear tape stuck on the fiber end allows you to see the size of the focused spot (Goggles may be needed here, but best to use a low power setting in case you fry the tape..). Insert the fiber after cutting the end with a new razor blade, a clean end allows more transfer so I used heat to melt the end shiny and clear.

I'm not sure how much power this fiber can take but due to its transparency and the melting point of 160c, I'm sure at least a watt can be put through this cheap fiber. Try burning clear plastic with your lasers focus at .5mm spot (Again, goggles..), it doesn't seem to melt at all. It may degrade the fiber with a 12x 405nm though due to wavelength.








Ready, set, glow!

Neat project! Very ingenious! Not many people here do much with fiber :/.

My buddy who helped with our openspectrometer.com project thought about using TOSlink as cheap spectrophotometer connections and probes and such. They are certainly the right price, and sure maybe not ideal for UV, but maybe "good enough" for a wide range of other purposes. They're almost cheap enough to be disposable if UV does degrade them, but you are in a pinch and need UV.

Apparently the acrylic is transparent to 370nm and opaque by 300nm, there is little drop in output using 1.5m vs 10cm.

Time will tell if 405nm ruins it, but its not UV really, just a deep violet colour.

nmz787 said:

My buddy who helped with our openspectrometer.com project thought about using TOSlink as cheap spectrophotometer connections and probes and such. They are certainly the right price, and sure maybe not ideal for UV, but maybe "good enough" for a wide range of other purposes. They're almost cheap enough to be disposable if UV does degrade them, but you are in a pinch and need UV.

Click to expand...

Whatever happened to that project? I haven't heard anything about it awhile.

Any ideas on easily focusing into a 100um fiber?

Anybody have any divergence figures for different core diameters when using our hobbiest-sized lenses?