Building A Simple High Voltage Nitrogen Laser (Ft. StyroPyro + giveaway)

When Theodore Maiman invented the laser in 1960, it changed how we looked at light. Finding use in everything from corrective eye surgery to analytical DNA sequencing, and of course even manufacturing, they're legit. As complex as they might seem, there's actually a really simple form of laser that can be built in like a single evening. It's called a TEA laser. It's nothing like your standard laser pointer. Foil, plastic sheet, and some supplies from a Add the appropriate power supply, and it gets you this. However, don't be deceived by their simplicity. Deep down, TEA lasers are evil little black holes of free time. But they're totally awesome, so I built one. Let's go. Before we begin, Keysight Technologies provided several 4-channel oscilloscopes, which I'll be giving away after this video. They're also giving away $300,000 worth of equipment during their free Keysight University event. So stick around to the end to see how you can grab one of these sweet puppies and sign up for the Keysight University event. Now the TEA and TEA laser stands for Transversely Excited Atmospheric, which is basically just fancy nerd talk for sparks along the length of an electrode at normal room pressures. They're all built approximately the same following this schematic. You'll see one shared capacitor plate on the base and two separate capacitor plates up top, separated by a lasing gap, yet connected through a resistor. A formal spark gap bridges over that dielectric in the middle. Sparks means high voltage, so the power source I decided to try this with was a 15kV supply from a past video of mine. Man, this thing is really turning out to be useful. I did a fair bit of reading on the topic, including looking at how others had done this in the past, and got to work. My first attempt used an 8x11 sheet of foil, a matching projector sheet on top, two 3x9 foil sheets on top of that, and two sections of aluminum L-channel. On top the L-channel sat a high-value resistor. For the spark gap, I attached a wire to the bottom foil, and just let it hang right above the top foil. Building it was only half the battle though, considering the light it puts out is UV, and we can't normally see UV light, that kind of makes the testing and seeing if it works right a little difficult. The light has to hit something that'll fluoresce. Thank god for highlighter ink and water! No, this isn't pee. Turning it on, I blew my eardrums, and there were sparks all across the lasing channel, but no lasing. None at all. I tried increasing the spark gap so that more power built up, and all that seemed to do was damage my hearing faster, and cause the plastic insulator to fail. It literally started to melt. So, after repairing it, I reduced the spark gap, but widened the lasing gap. Starting at 1mm, I moved it out in 1mm increments, thinking perhaps that would cause it to laze. Still no cigar this time. I was thinking, well, hey, maybe my electrodes are the problem, so I tossed out the aluminum L-channel, and replaced it with this solid hex bar. The hex bar was cut from 8mm allen wrenches, which, uh, turns out is pretty hard to cut. I read that this has been successfully used before, so I figured, um, you know, I'd give it a try. I also replaced my janky spark gap with a more permanent lower inductance version built of two steel bolts. This time, the setup felt good. It looked really solid. With the hex bar being 6 inches in length, I trimmed the top foil to match, and placed it all on a 7 inch square base. After turning it on, the gap finally filled with transverse sparks, which is a good sign, but still no lasing. I tried a few different lasing gaps with 2 and 3mm, giving the most uniform discharge, and sparks are nice, but lasers are cooler. So I asked my friend StyroPyro for some suggestions. He, uh, likes lasers. You gotta come up with a way to make an incredibly fast pulse. The lifetime of nitrogen in the excited state is extremely short. It's like 2 or 3 nanoseconds. So having it flat is a big thing, because you're minimizing, uh, equivalent series inductance, you know? Is that why you need a smaller capacitor so it has a higher, like, frequency of discharge? You can, you can make it bigger and have more area, but I guess, like, I don't know if you can see, I don't know if you can see this at all. Yeah, you got sand electrodes really, uh, really nicely and smooth there. I've spent, like, a week on this. This is the simplest project, dude. Funny, because the same thing happened for me, because I just, I, I kept messing with it, I could not get it to laze, and, like, every once in a while I'd maybe shoot out one working pulse, and it's like, oh, I got it, and then it stopped. We went on to compare the differences in our setups and what I needed to do to improve mine. I ended up flattening out the foil to get rid of all wrinkles, and used 500 grit sandpaper on the edges of the hex bar. Apparently TEA lasers are finicky little beasts, because now it worked. Turning it on this time, there was a clear laser shining right through the water. Super cool. The beam can also be seen if it hits white paper due to the fluorescent dyes that are used. Stepping back about three feet or so, the beam was actually still fairly focused, and this is when I accidentally discovered my shirt apparently fluoresced as well. And this was my favorite shot. You can clearly see the beam extends out. You're looking down the barrel of a nitrogen laser, which is also a hint at how it works. Electrons leave the aluminum, and they smack into the nitrogen, which excites it into a higher quantum mechanical state. And then as the nitrogen starts falling back down to the ground state, it releases a UV photon. And if you build it correctly, you have a lot of excited nitrogen in a row. As one photon leaves the molecule, it stimulates the other ones to fall out, and you get a big pulse. In fact, it's actually so good at this you don't even need mirrors. Now tell me that's not cool. You know, building this laser has given me a totally whole new appreciation for how lasers work. And if you decide to build a TEA laser yourself, unless you want to join the Let's Go Blind Club together, make sure you wear a pair of UV blocking safety glasses. And since this involves high voltage, you know what that means. One-hand rule. It saves your life. Okay, you've learned how to make a lazy beam, but honestly, why stop there? Keysight is launching an epic event called Keysight University Live, which is pretty much like Christmas morning at Tony Stark's house. Not even kidding. I'll let my friend Daniel from Keysight tell you the fun bits. You could have a lab like this for free. Seriously. Sign up to win over $300,000 in test and measurement gear as part of Keysight University Live. Hear from industry experts, get a sneak peek at never-before-seen test gear, and win some for yourself. Sign up now. You can use the link in the description down below. On March 15th, they'll pull their first round of winners and reveal a new series of benchtop gear, including signal generators and power supplies. So it really makes no sense not to sign up. While you're at it, go check out Keysight's YouTube channel because it's full of really good content. Okay, as promised, I'll be giving away several of these four-channel oscilloscopes. Here's how you can enter to win one of these sick rides. First, smash the like button on this video. Then comment down below with your thoughts on this project and what projects you'd like to see me tackle next. I'm also allocating a couple scopes to my Patreons as well, so choosing to support my work through Patreon doubles your chances. I'll choose three viewers through the comment section and contact you through their YouTube or email, so you better respond. Well, as always, this video was a complete pleasure to make, and hopefully it was a pleasure for you to watch. Thank you for watching, and I'll see you next time, you classy cats.