Les' Lab - 2020-08-06
Episode 5 #laser #optics Check out my other videos: https://www.youtube.com/leslaboratory Please don't forget to like,subscribe and comment for more great content! If you found this content useful, and would like to support this Channel, please consider supporting this work on Patreon: https://patreon.com/leslaboratory Or donate directly: https://paypal.me/leslaboratory Alternatively, please share this content on your social media platforms, it really helps me out! In this video, I show three of my high performance designs for Home made TEA nitrogen Lasers. Although Nitrogen Lasers are quite simple to build, they are difficult to build well. My first ever TEA Laser was held together with gravity and glue. The ones demonstrated here are worlds away from those first attempts! The two Charge Transfer Lasers demonstrated, have high repetition rates, high output powers (peak and average) and are robust, with many thousands of shots possible before the dielectric has to be replaced. These can easily drive a Dye Laser to threshold, in fact the peak power is so high, Dyes can be Lased Superradiantly (Feedback is so high, no mirrors are needed!)
"you can make it yourself" says the guy that makes commercial lasers. Just discovered the channel, love it
You can! These are not commercial, designing and building them for me is just a hobby :-) My day job is with Computers. Glad you love the channel, more cool stuff is in the pipeline for electronics/science/computing fans!
This is the only professional nitrogen TEA Laser I've seen on the internet for DIY...
Thanks! Glad you like it!
There's another channel...i think it's rocket laser or something. He is pro
@@johnnycash4034 Yes, Swissrocketman. He designed commercial N2 Lasers for CERN!
Thank the Lord! Finally another channel on YouTube with some great laser content!
Yep, there should be more on here! Thanks for your support! :-D
After watching the video, I wanted to assemble this design. The idea of using a spark gap with air removal is especially interesting.
Amazing and jaw-dropping to watch and listen to you! Thanks once again Les, not only you are inspiring but your explanations are crystal clear and very entertaining and full of insight. Just Perfect.
I CAME.... to appreciate your knowledge and passion! Love your videos!
Hope to see more DIY tea/nitrogen stuff soon! Your channel has become one of the best and my most favorite! It’s the only channel that’s inspired me to work on my own projects in a very long time
Awesome thanks! There is yet another Nitrogen Laser video in the works...
@@LesLaboratory can’t wait! You’ve got me interested and motivated… I’ve had the chance to get into this stuff before and never did… now I’ve caught the bug!!
I love your plumbing fitting spark gaps.
Thanks! The good thing about constrained by a micro budget is knocking zeroes off of the prices of commercial equivalents!
Thanks! Educational and entertaining at the same time (in a science geeky kind of way). 😃
26:00 Amusingly, YT auto-captioning took the discharges as [Applause]. Quite apt, though! 😆
BTW, since the gas feed is set up, it may be interesting to try gases other than N2.
Regarding the dielectric sheet, often they may have tiny imperfections, creating weak spots, where breakdowns eventually occur. The usual measure to mitigate these to have 2 or even 3 layers of the dielectric, layered together. That is, 3 sheets can perform more reliably than 1 sheet of 3 times the thickness.
Thanks! Regarding the dielectric, this is solved by redesigning the circuit, such that it is not under permanent stresses (charge transfer scheme). Alternative gasses are in the works, I have optics for this on order, and manifolds in my basket 😉
@@LesLaboratory , impressively quick answer to a comment on a video posted 3 years ago! 😃
Standing by for watching more laser experimental goodness!!
Found your channel just recently. Really awesome video here. I built the SA type version of the TEA N2 laser in junior high MANY years ago. I got a huge kick out of this video (and the dye pumping finish was super).
The aluminum hex bar extrusion is such a good idea. I imagine the edge tolerances are great for the purpose.
Thanks! Yeah, I built the SA one too (except with doorknob caps). I actually still have it in my cupboard, along with a copy of "Light and its uses". There is nothing more satisfying than building something like this truly from scratch.
I tried a number of profiles (I now have a whole box of various shapes), but hex had the best performance and was above all easily repeatable. Edges aren't bad, but I give them a light polish with 000 grade steel wool before use.
Long pieces bend a little, it would be nice to be able get flat bar with a 120 degree knife edge on it instead.
Cheers!
@@LesLaboratory I heard that the N2 laser...fron "light and it's uses" & from "the amateur Scientist" (Scientific American) Can't work properly due to the high inductance of the thick insulation between the copper. It was also copied and sold as "PLANS" by 'Amazing Devices' This guy even used the same sketches...
If you've got it running with a little corona in the dark, try squirting it with some canned air. Make sure it's the refrigerant type and not flammable. The former should suppress the corona nicely and the latter make everything more warm and orange. The refrigerant type should be interesting to try in the pressurised spark gap.
For sure. It would be interesting to try SF6 as well.
Build a professional TEA 2W Nitrogen laser so seeing those mini lasers with capacitors was very cool.
Great job, thanks for sharing!
Really amazing work. I gather that this fellow might be a chemist for his access to the cuvettes? Very common tool for FTIR work.
When I was young, I was very curious about everything what's new in the field of laser technology. my first device was a helium neon laser from Conrad Elecronic in Germany. it cost 400 German marks at this time. not to be compared with laser pointers for a few DM, which were available on every rummage table a short time later. but I had never lost my interest of this cool hobby. you rarely get useful offers on eBay that can be paid for and are still useful. I just googled what a laser cuvette costs. 338 euros for one peace... unbelievable... Thank you for your amazing work. 👍
Thanks! Yeah eBay prices for these things can be insane!
You can get Quartz cuvettes from China for around 35 Euro that are usable (though they leak over time as they are frit-bonded). Fully fused quartz cuvettes can also be had from China for about 100 EUR.
@@LesLaboratory ah, many thanks for this useful Information. Maybe I bye some for my own experiments. I have to laser dye from the past.
How does the cuvette for the Rh6g become directional without silvered windows or mirrors?
Great job Les
a physics question on the dye laser:
knowing that the medium is suspended in a liquid, how can we take into account the motion of the lasing particles?
in room temperature there is brownian motion, and during energy absorption/light emission there could be recoil
is it safe to approximate the particles as stationary as to not affect the frequency of emitted laser light?
I doubt it matters, though it would be interesting to look up! If you were to assume the molecules were moving at the speed of sound, stimulated emission will be orders of magnitude faster, so much so, that it would be safe to call the speed of the dye molecule zero. Lasers exist, where the gain media is moving at supersonic velocities (chemical oxygen iodine springs to mind) and even in those, molecular motion could be considered slow to zero as far as photon interactions go.
This video is a good example btw. RE color coordination, you got the outside light shining in with 6000K at noon, the overhead lights have around 3000K, and because of the harsh shadows from the bright outside light, the camera is constantly pumping because of exposure changes when you move your hands around.
Solution would be to completely block out the outside light, have your overhead lights at 4000-5000K, have the whole setup on a table, best is a light-gray background/surface, and some additional directed lighting at the same color temperature.
Other improvements would be to put up the schematics as CAD/EDA drawings. Marco Reps for example often shows SPICE animated simulations. Unless you can pull off hand-drawn schematics as good as Big Clive.
Thanks again.
I have ordered a couple of small 5600k lights for close up work and consulted the camera manual re white balance. As funding permits, I will invest in a proper lighting setup. It will be interesting to see how color rendering work with laser beams, they are notariously difficult to film with good color reproduction.
@@LesLaboratory Yes, lasers are difficult, especially since you're often working with low-powered ones. But for all the normal camera work, not having enough light always works against you. At 60 fps, the sensor only has 1/60 of a second to collect all light. If you are underexposed, you can crank up the ISO, but that introduces more noise into the picture. Or open up the aperture, but then your depth of field gets shallow. So the best thing is to just have a lot of light to begin with (and a good lens of course, but I assume you're just using the variable stock lens).
Best would also be to lock exposure, but that can be problematic if you want to be behind and in front of the camera at the same time, so having consistent lighting somewhat mitigates that.
Much sturdier design - has given me some impetus to build a better one.....
It's fantastic!
Thanks!
I think it deserves video explaining advantage and disadvantage of this laser
had the same problem as the first shown design with my diy transistor, used a to thin dielectric so eventually it burned through it.
That's sick!
20:30 Also... There is a smiley face.
Is nobody else going to mention that his dyes have little smiley faces on them?
LOL I noticed that in post, there are 2 printed squares either side of the label and the meniscus is the smile. They are happy little dye cells!
@@LesLaboratory Haha! "They thought we wouldn't notice, but we did."
Great video!
Thanks!
i wonder if you could somehow get a faster pulse rate without killing the output power, would be cool to have a Constant output N2 laser, but those pulses are what excites the N2, i do wonder if you could get it to trigger like 30 times a sec though
I can get a good 60Hz out of the smaller version of this Laser, but yes, you are right, if you cool the gas, you can increase the repetition rate. Back in the 1970's Nitrogen Lasers were built in Labs that could fire at kHz rates with cooled N2.
@@LesLaboratory on wow that’s interesting, would be cool to build one, but I lack materials to build a nice one lol
14:54 Unreal Tournament 2003. I see you are a man of culture. 😎😎😎
Of course! :-)
The British guys like the tea laser
Can't start the day without good tea!
Fantastic ! just found you and subbed, built a Nitrogen laser many moons ago very primitive but did Lase, been in love with laser light for as long as I can remember (like a lot of us ! ) gonna check out your other vid's hope there is a schematic for your power supply's there...cheers !
Yeah, it's addictive! There is a video here of the PSU: https://www.youtube.com/watch?v=GbQEan4gwWM no diagram, but a real easy straightforward build! Thanks for your sub!
I love the suggestions and it brings back lots of memories but watching these raised a few concerns. I used these and other types of laser right up to class IV in PhD for fluroescence spectrosopy. Please please mention safety goggles etc as there are lots of hidden dangers here, these are on an open bench, your lasers are not secured and I see no interlocks etc. They operate at UV 337nm and the peak power can do some serious damage to anyone not just the operator so you need googles to protect the eyes. Even the dye cell output I would expect is in the same category. Reflecting either off a surface into the plane of the eye so it can be seen, it doesn't bear thinking about what might happen! A split-second direct exposure to such a 200 mW laser emitting even if it were 100 metres away can cause permanent eye damage. Pulsed UV radiation from nitrogen lasers is definitely capable of causing eye damage before you even mention the dye cell output frequency shift. The laser pulse or beam may damage the eye before the eys will have even reacted that is the danger of these. Of course noone thinks it will happen to them, but it can and the damage is often permanent. The high voltages are an issue too they can kill.
Thanks. In later iterations, the Dye Laser is Mounted on on optical breadboard, where all beams are terminated. Goggles have been mentioned in the comments and since there is a lot of Laser craziness on YouTube, I had already suggested that this will be addressed in due course.
The classification of this Laser would be 3B. Although peak power (in watts is high) pulse energy is on the order of micro-joules and average power is sub 20mW.
At this wavelength, UV would never penetrate the cornea, that said, a corneal ulcer is exceedingly unpleasant, and eye protection should be worn.
The Dye Laser on the other hand could damage ones retina if you chose to stare down the beam.
All Laser beams diverge to some degree. At 100m distance for a 200mW Laser as you suggest, with a reasonable 0.5mRad Beam divergence, would yield a spot size of over 50mm, giving an irradiance 0.097mW per square mm at the target. Assuming a person had dark adapted eyes, for a pupil diameter of 7mm, this would equate to approximately 3.7mW of Laser light entering the eye. A moderate hazard, but hazard nonetheless.
The High voltage supply, whilst it deserves respect, is quite low current. It would give a nasty shock, which could lead to an accident, but is highly unlikely to kill. This is in stark contrast to the danger posed from a Flash-lamp Pumped YAG power supply, which are positively lethal.
@@LesLaboratory OK I was dealing with class IV Nd:YAG with primary a 1064nm and the more familiar green 532nm both were high power. The pumped dyes were 400nm up to 980nm so seems like lots of similarity.T This was 17 years ago now.
@@dombaines I have a great respect for Nd:YAG, and have built several. One is doubled to 532nm, and pumps an unusual solid sate dye Laser.
In any case, point taken, so thanks for reminding me about safety! It is something that is not adequately covered on YouTube, especially how to purchase the correct eye protection for the job, so I will delve into correct wavelength and Optical Density selection for Lasers.
Cheers!
Les
Do you have any videos that explain the square "bottles of dye" or what look like this?
I don't understand the beam coming out at 90 degrees from the beam going in.
If these are simple glass containers and if the inner glass surfaces are actin as the partial mirrors on each side of the lasing liquid.
Or maybe there is a mirror off camera or housed in the assembly holding the fluid.
And am guessing there are mirrors or something in the dye containers that I am missing.
Thanks.
Do you have any high power argon lasers? I know they are extremely inefficient and huge, just wondering. I love the multi spectrum beam they emit. They are my favorite laser by far.
No, just this small one here: https://youtu.be/yYIft-1WCYE
They show up on eBay from time to time, and I have been tempted, but power and space is an issue at the moment.
Nice info , thanks :)
I would make a modification to this if I had the resources laser the UV laser to a GAGG crystal and set up optics to excite the GAGG to lase and hopefully get a bright yellow beam.
Deal with lasers alot and own many lasers and very powerful co2 and yag ones. I never been into these tea lasers. Always thought I should make one but never have. Just find they have not much use to them and seem outdated in a way. I’m sure they are fun to make but I think to make a good one you need to spend the money and time on quality parts.
Cool! Depends what you want one for. I always wanted a tunable Laser and a TEA Laser pump seemed to be the way to go. See this video here: https://www.youtube.com/watch?v=-ny_-Y1MpRY
These home made N2 Lasers exceed the specifications of commercial units of a comparable size. The latest iteration produces 0.5 Megawatt Peak power with an average power of over 10 Milliwatts. You can see the measurements here: https://www.youtube.com/watch?v=ZQJoJEr3US8
@@LesLaboratory sorry not putting it down I know it takes some work it get it spot on, it just one of them lasers that’s hard to do something with. I know they can be powerful, I seen them in the work place cutting, etc, but they are big ones and I mean big. I know people use them of the interest of its wavelength and dye as you show in your video. But must say I think your video is one of the best for show this laser in more detail. Also wonder if you could improve them more and take it to a better level ?
@@michaelmitchell8218 No offence taken! and thanks! Yeah, I want to up the game a bit. My goal is to try and squeeze a lot more power out of it, I know it can be done, but it starts to get real tricky. Channel length can't be reasonably extended beyond 30cm or so when running at atmospheric pressure, but there are tricks like Like having two or more channels in series (MOPA configuration) or Marx Bank switching. Beyond that we end up in voodoo transmission line territory with coaxial feeds and water capacitors.
This is really cool! Subscribed
Anyhow a question: Does the spark gap produce much EM-noise in radios or TV? If yes, could that be shielded easily? With a metal case or something maybe?
Awesome thanks! Yes, spark gaps (and even semiconductor switched Nitrogen Lasers) radiate loads of EM-noise, so an analog radio or TV, will 'pop' or display static. It will interfere with digital equipment as well.
If this was built into a metal case including the PSU, you can easily minimise the interference significantly.
After that, you may have to add line filters or ferrites to the input power leads to minimise leakage that way as well.
Fantastic work!!! 24:08 How do you get the uniform discharge like that? Is this at atmospheric pressure? How are the edges prepared?
Thanks! Yep this is at atmospheric pressure. The edges are polished with 000 steel wool. You get a nice smooth discharge with nitrogen assuming everything else is tuned correctly. With air, not so much, but but it is doable.
This is really cool！
You talked about scaling the laser down, but what about scaling the design up? I am wanting to build a single pulse setup that it capable of ionizing a channel of air.
in this video: https://www.youtube.com/watch?v=ZQJoJEr3US8 I demo a 30cm long TEA nitrogen laser that outputs half a megawatt. TEA lasers don't scale very well though. for higher powers you would need a low pressure design.
To ionize air channels, I'm pretty sure you need well over a Megawatt. I believe it has been done with excimers.
Is the intent to get it to conduct high voltage?
@@LesLaboratory I am interested in the possibility of using a nitrogen laser to direct the output from a large Tesla Coil. I have a very large HV cap. I just didn't know if it would be suited for this purpose. The cap definitely has the energy capacity. 83,520 Joules. (No that isn't a typo. It's rated 24KVDC @ 303.8 Mfd. It weighs 400lbs).
@@Kilroy01 Now that is a capacitor!
Unfortunately, its not about how much power you have available, but how fast you can dump it into the channel. This has to be done on the order of nanoseconds, which necessitates low inductance, low capacitance values.
You could build a Large Q-Switched Nd:YAG with it, and triple the output with non-linear crystals...
I wonder, how much power has the ouput a few miliwatts ? do you need some eye protection ? I mean it is always good, but is i a must for this ?
On the charge transfer type, doe the rail without the film cap connect to ground? Despite the words of " It's not going to exactly make a laser pointer " that's what I am attempting to do. I have tried making several small N2 laser heads this last 2 weeks. Been posting about it on my community tab. It's been kicking my backside!
Found my answer in a write up that you inspired!
Sorry I missed this comment! Yes, it connect to ground (but you found that ;-) ) Well, I mean, if you were super determined, and wanted to have a go at making a rolled capacitor....
@@LesLaboratory I am super determined that's for sure!
I think the size could be further reduced, but I'd have to know what the effect of scaling this device is.
For example, how much less voltage is needed when substituting razor blades for the hexagonal aluminum rod?
Potentially, a feedback oscillator driving the spark gap could be used to step up a low voltage power supply. The feedback oscillator could be substituted for a simple oscillator used to drive a transformer with a few more components.
At that point commonly available capacitors could be used to avoid the issues caused by the homemade version.
Of course this greatly reduces the output, but given the insanely high wattage of the typical TEA laser, it may be worth a try.
EDIT: The size I'm envisioning is comparable to an old Nokia "candy bar" type of phone, including the powder supply.
Sure, I suppose it could be made much smaller. I do not think a razor-blade channel would be quite as helpful as you think. Whilst such a channel would lower the voltage, it would also lower the available electron energy I imagine. I have previously used sharp channel electrodes, and found them to be very poor in this application.
It could be shrunk to the size you describe. I think a channel of ~3cm is practical. After that, it is just a case of shrinking the rest of the package. Small HV PSU's are readily available, I just wouldn't expect a huge repetition rate.
@@LesLaboratory
Thanks for the information on practical scalability.
Your response was much more in depth than I expected.
I didn't expect razor blades to produce anything useful, I was just hoping to get a relative figure in order to get me in the ballpark when I build the power supply.
I don't have a whole lot of space for projects, so the smaller the better.
Like you, I'm opposed to building something that's so structurally unstable as the typical TEA laser.
Better to spend some extra time in the design phase & not have to readjust everything each time the laser is moved.
I'll happily accept a vastly lower rate of repetition in exchange for increased durability & the ability to use off the shelf components.
@@kaisersose5549 Totally. These builds are great in terms of stability.
They don't scale up too well either. I have built one with a 30cm channel, but for TEA designs, that is more or less the upper limit.
Scaling down is something I should look in to. 6cm is cute, but it would be cool to get it down to 2cm, and still be able to do useful work, i.e. pump a dye laser.
I am also looking at trying to replace the doorknob caps with something more obtainable as well. I have tried removing epoxy from wire ended HV caps, but always manage to damage the dielectric and it is a lot of work, so I am looking into a design comprising of bog standard wire ended HV caps. I reckon with a bit of thought and care, it can still be made to work!
Hope not to be boring, but I'm wondering if the pk cap is replaced with a doorknob as the ones used in the dumper, would the performance be better or basically the same? If it is the same, I guess the 'only' advantage on using a doorknob as peaker is the compactness and robustness of that vs aluminum foil+acetate sheet DiY peaker?
Wouldn't it be easier to ditch both circuits and drive the lasing spark gap with a TIG Welder in such a way to distribute the high current across multiple lasing gaps and collecting all radiation with sustainable mirrors/prisms ?
Long time ago I built weird nitrogen laser with copy of the diagram from PRA-LN100 laser (TEA). But, after marx bank generator consisting of only two stages (to doorknob capacitors), there is 15 m of 75 Ohm cable feeding to the laser head. No additional spark gap on the laser head. And since then I lost interest in building any laser. My bad.
Cool! Do you have any more information on that?
Great video! Quick question - what is the effect of the feedback mirrors on the dye laser pulse energy? Should one include feedback mirrors to fully optimize the pulse energy?
Using feedback mirrors will significantly improve beam quality, stability and pulse energy. some feedback is a requirement for tunable Dye Lasers (check out my other videos) the required reflectance of the output mirror is fairly low from 10-50%
@@LesLaboratory thanks. Don’t the surfaces of the cuvette itself also already provide some feedback? For example, the power reflection coefficient at air-glass interface is already ~ 4%
@@poodook yes, they do. In my Dye laser designs, I have the cuvettes tilted such that the reflections don't interfere with the beam.
So it doesn't need to be Q switch since it's already in Pulses form ! ! right !! ??
It is already pulsed and probably under 1 nanosecond.
Very powerful, could it burn if focalized on the target?
@thethoughtemporium - 2020-08-10
That. Was. Amazing. What a phenomenal improvement to the usual TEA laser setup
@LesLaboratory - 2020-08-10
Thanks very much. Best of all, there is nothing particularly exotic in the builds, except perhaps the doorknob caps!
@acompletelynormalhuman6392 - 2020-09-22
You could make a more powerful TEA laser using this design and then make you even more Quantum entangled particles
@LesLaboratory - 2020-09-23
@@acompletelynormalhuman6392 One is in the works at the moment with a 30cm long channel, just waiting on parts arriving. They tend not to scale up particularly well from what I understand, but we will see how it goes!
@Jonodrew1286 - 2021-04-14
I second that - my output was pretty good, spark pulse felt like it was in sync with the nerves in my teeth and UV dot was not too shabby - though I have to admit it was massively Heath Robinson - shame I cannot up load any video here! 😅😅
@1islam1 - 2023-03-01
@@LesLaboratory ⚠️ God has said in the Quran:
🔵 { O mankind, worship your Lord, who created you and those before you, that you may become righteous - ( 2:21 )
🔴 [He] who made for you the earth a bed [spread out] and the sky a ceiling and sent down from the sky, rain and brought forth thereby fruits as provision for you. So do not attribute to Allah equals while you know [that there is nothing similar to Him]. ( 2:22 )
🔵 And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a surah the like thereof and call upon your witnesses other than Allah, if you should be truthful. ( 2:23 )
🔴 But if you do not - and you will never be able to - then fear the Fire, whose fuel is men and stones, prepared for the disbelievers.( 2:24 )
🔵 And give good tidings to those who believe and do righteous deeds that they will have gardens [in Paradise] beneath which rivers flow. Whenever they are provided with a provision of fruit therefrom, they will say, "This is what we were provided with before." And it is given to them in likeness. And they will have therein purified spouses, and they will abide therein eternally. ( 2:25 )
⚠️ Quran