Home-Brew Ruby Laser Packs A Wallop

In the past half-century, lasers have gone from expensive physics experiments using rods of ruby to cheap cutting or engraving tools, and toys used to tease cats. Advances in physics made it all possible, but it turns out that ruby lasers are still a lot of fun to play with, if you can do it without killing yourself.

With a setup that looks like something from a mad scientist movie set, [styropyro]’s high-powered laser is a lot closer to the ray gun of science fiction than the usual lasers we see, though hardly portable. The business end of the rig is a large ruby rod nestled inside a coiled xenon flash lamp, which in turn is contained within a polished reflector. The power supply for the lamp is massive — microwave oven transformers, a huge voltage multiplier, and a bank of capacitors that he says can store 20 kilojoules. When triggered by a high-voltage pulse from a 555 oscillator and an old car ignition coil, the laser outputs a powerful pulse of light, which [styropyro] uses to dramatic effect, including destroying his own optics. We’d love to hear more about the power supply design; that Cockcroft-Walton multiplier made from PVC tubes bears some exploration.

Whatever the details, the build is pretty impressive, but we do urge a few simple safety precautions. Perhaps a look at [Ben Krasnow]’s 8-kJ ruby laser would help.

28 thoughts on “Home-Brew Ruby Laser Packs A Wallop

    1. Cube sat to put a cd on the moon… maybe. Although compensation for air disturbances. Never mind.
      Maybe taking down unwanted drones? Add a couple more banks of capacitors and increase the firing rate. Send it into a loop. Adjust to make the pulses overlay the gaps so it’s effectively a longer pulse for the duration of the loop. [ watch for time distortion as it creates drag and both the earth and the solar system are moving fairly quickly. ]
      Perhaps pumping a larger laser?
      Maybe spread the beam put it through a full sized lcd display and then focus it back again.
      Display an image on the screen and instantly print it onto wood or plastic in the blink of your one remaining good eye.

  1. That’s awesome.

    When was in high school I attempted to build a nitrogen laser from an American scientific, but thankfully my electronics ability wasn’t good enough to get the high voltage power supply running.

    I’ll have to have another go one day – I could do it now :-)

    1. Wasn’t that Amateur Scientist? Easily could be wrong, long long time. Water aspirated low pressure nitrogen laser with a capacitor made of a 12″ x 12″ double sided pcb with gap on the top over which the chamber was built, charged to HV till spark gap on one side discharged cap creating a wavefront of potential difference at speed of light synchronized with the position of the lase pulse for amplification whole length of the tube. Didn’t get to finish it at school. School confiscated it moment did first hv test, everything was on track. Got it back weeks later well after science fair. Some weeks after that suspended 2 days when had a 90V battery in class to demonstrate just simple NE2 blinking ckt… teach wanted something “safer” than the HV and Dad guided, but friend bragged he could touch it to his tounge because it looked just like a giant 9v… and he could take it, did it lots of times. Snatched it outta my hand and tried. Backflip! GO HOME! That wasn’t a great year.

      1. I remember a detailed article in the April 1990 issue of Scientific American on how to build your very own pulsed laser. I tracked it down on nature.com, it was called: “A homemade copper chloride laser emits powerful bursts of green and yellow light” by Jearl Walker. As a kid, I remember being fascinated by that article and even trawling the local tip with a shopping list of discarded quartz heater tubes and lighting transformers… Helium and some of the chemicals involved would’ve been much more difficult to come by for a kid in the early 90s though. Still, on paper, this laser looks like an easy enough build!

          1. Actually if I remember from the article, the mirrors were just two glass slides covered in kitchen foil (one with a pinhole?). That’s how forgiving this build seems to have been. I can imagine that just about seeing it pulse some laser light in the dark would’ve been an achievement in itself back in them days. What was really fascinating to me (as a kid) was that, here’s a bunch of stuff other people have discarded, if you reassemble it just right, you get something very few other people get to play with at home. I don’t think we’ve really moved on from that 30 years on ;-)

  2. I got a nice ruby rod laying about and loads of optics and stuff. Also got a big yag and small yag too must get round to doing something with them. Not the best ruby laser I seen.Very out of focus for its shot and the big power bank is a overkill could make it a lot better but he does say it’s all made out of parts laying about. Just hope he don’t leave that power supply exposed for people to get to it. Needs a better setup that’s safe to others.

    1. Ruby laser is not very efficient, thus very big energies needed to excite ruby laser rod. So power bank must be that big if you want high pulse energies. The power setup it is simpliest by components, that not involves SMPS techniques. I think safety precautions must be admited by individual, not by the maker, who make most off all for show.

      The most obscure thing that, as many solid state laser DIY makers on the internet use these lasers for shooting razor blades. Common.. Is there any real purpose than shooting “Gilletes”?

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