ฝัง
- เผยแพร่เมื่อ 14 พ.ค. 2024
- Episode 59
#photonics
#Laser
In this episode, a sub $30 dollar junk tattoo laser is torn right down, repaired and re-assembled into a bench-top instrument.
During the repair, theory is covered, as well as some practical alignment techniques.
A home made, high voltage power supply is constructed for it, generating 100 Joules for the flash-lamp.
The final Solid State Q-switched nanosecond Neodymium:YAG Laser has megawatt level peak powers, capable of vaporising materials, generating plasma in the air, and frequency doubling to green.
Power measurement is done using a Joule Meter, a fast picosecond risetime photodiode, and an oscilloscope, with some very surprising results!
Check out my other videos: / 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: / leslaboratory
Or donate directly: paypal.me/leslaboratory
Alternatively, please share this content on your social media platforms, it really helps the channel!
0:00 Intro
0:43 Overview of the Laser
3:24 Diagram and explanation the Laser
5:11 Tear-down of the Cavity
5:22 Extracting the Xenon Flash Lamp and Laser Rod
5:52 Examining the Neodymium rod and Xenon Flash Lamp
6:40 Corrosion and gunk
8:07 All cleaned
9:02 Replacing the mirror mount
9:38 Mounting Base
10:20 Finished assembly
10:31 How to Align a Laser
11:15 Safety First!
11:43 Home made High voltage Power Supply
13:57 Laser connected
14:24 First Light and final alignment!
15:54 Q-Switching!
16:21 Laser induced breakdown
16:30 Frequency doubling!
16:43 Measuring the Laser Power
17:24 Analysis of the Laser output pulse
19:34 Pockels Cell
19:42 Future experiments
20:06 Credits - วิทยาศาสตร์และเทคโนโลยี
![🔴 [TRỰC TIẾP] U20 Thái Lan VS LPBank Ninh Bình | Cúp VTV9 - Bình Điền 2024 | JET STUDIO](http://i.ytimg.com/vi/3wRNdAy3DXs/mqdefault.jpg)
![พรากรัก - เต้ย อภิวัฒน์ [ Official MV ]](http://i.ytimg.com/vi/ShT2ltn8GBE/mqdefault.jpg)
Nice presentation on this laser! The Cr:YAG saturable absorber does indeed behave as a relaxation oscillator, producing a neat pulse train. However you may find it difficult to get a giant pulse out of it - these saturate at an intensity/flux set by the Cr doping level. Increasing the flux by shortening the pulse (same energy) should cause saturation more quickly, bringing the pulses closer together instead of merging them into one. However there are more variables involved with the fluorescence & absorption of the crystals so you could still measure some increase in the peak of each pulse - will be interesting to see what you find here. I currently have a large ruby laser on my desk, pulled from the garage after watching this vid so I will probably start restoring it and dig out the old electronics again :)
Thanks! That makes sense. I will have to keep an eye out for a Pockels cell. I winder though if the cheap coatings on the optics would survive a truly giant pulse!
@@LesLaboratory Yes i suppose you'll only know when the coating comes off :) Seems like the more powerful (although, also older) QS pulse lasers were using high speed rotating corner cubes as the HR, so no dielectric coatings involved other than AR. It's a matter of getting the rotation rate matched to the flashlamp pulse length and triggering the flash ahead of alignment. However the pulse length is probably a function of rotation rate as well, which might be good or bad - anyway a pockels cell of some sort would be another interesting vid to watch out for! cheers.
Yup to use a CrYAG you need to have a precise matched pulse forming network for the flash lamp to get a nice clean pulse output.
An acousto-optic modulator might also work - No high voltage included, but the drivers might be more difficult to find..
This is totally not what I expect from a typical TH-cam comment
These lasers are neat. I saw a video demonstration of one that had different crystal attachments to make it output different wavelengths depending on what color of tattoo ink was being removed.
You you can get KTP crystals for these to convert 1064nm to 532nm Green light. Some high end Lasers have Dye Laser attachments that can convert to Yellow, Orange and Red as well.
@@LesLaboratoryMine came with a 532 attachment and a 1420 nm attachment. The 532 nm is fantastic and can ionise air at the focal point. The head also importantly creates a focal point unlike when you run the head with no attachment. The 1420 nm is a bit more sketchy - I'm not sure what it contains or what it is doing (or allegedly doing). I think based on the very questionable instructions it is designed to be used for skin treatment with some kind of facial mask which is not included in the package. Even with a very nice pair of laser safety glasses I prefer to not tinker with this system too much as I do value being able to see.
My workplace (a UK aerospace company) made their own hybrid packages that used 741 opamp dies (back in 1978) mounted on a glass substrate which was coated with NiCr. A YAG laser was used to burn away the NiCr coating so as to make precision resistors for the circuitry around the 741 dies. Occasionally the LASER would require maintenance and it was crucial that the reflector was spotlessly clean (DI water used for the coolant) or the LASER wouldn't fire. The LASER was about five Watts output and even reflected light had the potential to cause blindness.
Thanks for the video and I admire the quality of your work in the PSU and enjoyed the presentation.
Thank you so, so, so much for this incredibly detailed explanation. I'm looking to build a laser for flow measurement out of these tattoo machines and I was really looking into the details before I bought one, but your video is so detailed I don't need to look any longer! I'll let you know once I've built it!
I love how you have simplified the elusive yag laser. Thank you great video.
Thanks! I have some real nice projects in the works, based around it.
Do you know why I don't have people like this around me that are SUPER skilled in electronics?
We would get in SO much trouble doing stuff, we would become undoubtedly on some NO fly list. 😇
Great work!!
Awesum work Les as Always ;-) Really good explanation of the workings of this type of laser.
Thanks! :-)
Nice presentation, very clear and concise, with the right amount of detail in the different components and issues.
Thanks!
I really enjoy these videos. They bring back fond memories of the days when I worked at JK Lasers/Lumonics.
Thanks! :-)
what a nice project !
I know this is a laser video, but my mind is always blown at the level of detail and accuracy, over such small time scales that you can see with an oscilloscope.
An Oscilloscope is the most useful tool you can own for electronics and optics.
Another underrated channel! I love your content man! Engineering GOLD!
Thanks! Yeah TH-cam doesn't push it very hard, please do share! There is much more to come!
Oh man, what an absolute UNIT!!!
It's the SSY-1 killer!
Fascinating stuff
I can't wait to see the laser operated with the pockels cell and how you adjust it (electrically and optically).
I find LYE/Drain cleaner extremely effective at cleaning aluminium from corrosion but it does also make it kinda bright matte.
I've cleaned large sheets with it and even tho for my eyes it isn't very optically reflective, looking at it with my infiray thermal camera it is a mirror clear finish so don't think it would need any more polishing
Very nice! Ebay can be a treasure trove indeed. I once build a dual flashlamp pumped Nd:YAG laser with 350J stored energy and Q-Switched it the exact same way, from eBay and Alibaba party. The flashes in the air are really cool! Didnt measure the energy, but I think now I need to look out for a used Joulemeter!
Great video as always, Les.
Nice! Aliexpress and Alibaba are both excellent sources for parts. The Joule meters are dead easy to use. For the Gentec heads, you don't need the meter itself, just the head and an oscilloscope.
Recently I've watched a video of a lazer machine that are being use to make a high detailed carving arts and I assume it can also be done in huge stone figures damn it's so magnificent.
Please do a more detailed segment on the PSU! I have a similar laser i've been playing with, and i have a series trigger with simmering, i also sourced a large IGBT, so can do some very interesting stuff, such as single pulse picking, or high rep rate stuff.
Very good content, and good presentation.
I always worry that what I think will be an "improvement" will mess up some system tuning. I still have that skepticism, but measuring the output is good (but not complete) mitigation / verification for that concern. VLSI analysis could be a tool, but I don't know how fast the non-linear aspects stack up in optics.
This is a magnificent look at how one of these Nd:YAG lasers is put together! I was very interested to see that that actual cavity does not appear to be elliptical in cross-section. I would have expected the ellipse cross-section in order to better focus the coupling of the flash lamp with the laser rod itself, with each member at one of the foci of the ellipse. I suppose that given what else we've seen for cost savings in the construction of this unit, I should not be terribly surprised.
I now wonder, though, whether tilting the mill head to a precise angle would allow you to generate the correct elliptical profile. Of course that would be only the very first step in roughing out such a cavity, and you'd have to send it out for coating.
Thanks!
For diffuse reflectors, a precise elipse is not required, as there are no focal points to worry about.
Diffuse reflectors are considered superior in a lot of applications, since the light is evenly distributed, so no hot spots can build up in the rod. Diffuse reflectors can have reflectances much higher than any metal coating as well, leading to high efficiency.
You could probably mill out an Oval diffuse cavity at home.
@@LesLaboratory oh that's fantastic to know; I had not known about diffuse reflectors, but it makes good sense now that you've explained - thank you
Very interesting viewing!
19:44 the resistor between the output terminals has seen better days 😊
Well, it's a bleeder resistor, to bleed off DC voltage from the capacitor after the power is shut down, so as long as it's reasonably close in value, it'll still be OK.
That said, it is a safety component, so yeah, I'd replace it. Beats getting bit.
Oh man i can hear that high pitch freqency from accross the room
One thing that I've always wanted to see done , is the "electro laser"...the air is ionized by a high energy laser pulse, and at the exact same time a very high voltage discharge is sent down the same beam line , a directed energy weapon. I guess the feat of getting a single point in air to ionize as he shows here is not that hard, but to do the same thing along a say, ten or 50 foot length is entirely another thing, I would imagine with a powerful enough pulse laser it's do-able, also, I guess the target would also benefit the whole attempt by being grounded to complete the circuit.
I'll find a few samples here too show you. It exists. The real trick is making a pulse short enough. With the high fields and long pulse lengths it just doesn't work very well because it turns to thermal plasma with it being hot enough to essentially be metallic like in nature it will disrupt the beam propagation, reflecting and absorbing a significant portion of the beam. If the power is high and the pulse short enough then there's no time for thermal ionization and the beam passes mostly unimpeded. Easiest way to do that is with mode locking techniques. Not what's happening here.
th-cam.com/users/shortsFW4zFhnXj5o?si=K8-i8Mu8f1f7QnWh
th-cam.com/video/c20tz17SD0c/w-d-xo.htmlsi=B6dGbW0OeykiM8ce
I'm a bit surprised you don't sound so excited when laser came out with the first trigger. But thanks very much for the video
Fantastic to see it in operation - I was almost on the point of getting one of those laser removal units once to tear down but better sense prevailed 😂 If you’re having trouble finding a replacement cavity, then a PTFE cavity might work. I’ve never quite been sure on the relative merits of diffuse vs. speculation reflecting cavities, but there’s quite a few I’ve seen that use a Teflon or ceramic diffuse reflector. Might be a fun little machining project!
Thanks!
Yeah, I am still mulling cavity reflectors. I think they use compressed Barium Sulphate in these, its about as reflective as you can get, but PTFE may well be easier to handle.
Some manufacturer in China is bound to do Oval Ceramic section surely!
@@LesLaboratory 🚺👩🏾🦱@LesLaboratory 💬
🗨This Sheba Of AFL CIO Botswana Africa ○ Can The Lazzer Rod Can Us For AFL CIO Botswana Africa Research
↕️↕️↕️↕️↕️↕️↕️↕️↕️↕️↕️
Some of The grammlins Among Dead Black Conservative Could be Anti-statism & Anti aging Think There Popular Or Wana Be Popular Is Silent About Organizations Crime ⬅️➡️ Female Hotel Workers of Vanity Preacher
@@LesLaboratory 🗨@LesLaboratory 👼🏿
👼🏿 Orlando City SCgoalkeeper of Celestial Kingdom 🇧🇷 Can Is Be Use For Any Object ❓️ 💬
@@LesLaboratory 🗨@LesLaboratory 👼🏿
🚹🥷🏿IM Lack of Vanity Preacher Shhhhhhhhhhhh I'm Steve Schmidt's Vewier 🛡🏹 👼🪭🛡 Nontrinitarianism ➖️ Islamic Legion Mansa Musa 🟰 Utopian Overcomers Should Make Nikki Haley Vivek Ramaswamy Give Reparations To Navajo By NINETY-FIVE_THESES of Puck , Tatiana, The Bottom and The Battle of the Jericho Song💬
@@LesLaboratory 👼🏿 Orlando City SCgoalkeeper of Celestial Kingdom 🇧🇷 AFL CIO Botswana
👼🏼🇬🇭 CheckMate UAW-GRACELESS Of Ghana African Descendants 🥷🏼 🦸🏽♂️ Friedrich Douglas Liberators of Friend Just Find out About Creoles of color IS A Part of Femme fatale In Outside of Celestial Kingdom 💬
Very interesting, the mirror alignment was way simpler than I expected. I usually use a piece of paper with a pinhole in front of the illuminating laser so it's easier to see when the return beam is centered. Also some lasers can't handle back reflections so it reduces that too.
I'd like to see the details of your series triggering circuit, you skipped over the big string of diodes but I assume they are between the storage capacitor and the trigger transformer to protect it from HV?
I had thought so many diodes would add too much resistance to the current path but I guess not.
In Laser like this, if you are close enough, and pump it hard enough it will Lase. After that its a case of walking in the mirrors.
The series trigger I should write up. This was built iteratively, and the big string of diodes was to protect the main capacitor from the trigger pulse. I later dealt with the trigger Pulse, by coupling it to ground, before it gets to the capacitor by means of a small value high voltage capacitor. This works ridiculously well because the high voltage pulse is high frequency.
Thats soo cool to play with stuff like this. However im glad you are doing it, im way to chaotic to play with actual hardware, Ill just keep myself to the theory and let you show the results :D
Nice!
Great video.
About 15 years ago I missed out in a tank laser rangefinder on eBay. I found a cheap YaG rod recently but now eBay won’t let you buy anything laser related from eBay in Australia - despite non-portable non-battery powered lasers not being illegal.
I have not had too much trouble, however some of the military range finder lasers had export restrictions from the US. I do have one of the Hughes M60 Ruby rangefinder lasers… they have big lamps in those. Have never built a supply for it though.
Thats a real shame. I wish the legislators were suitably qualified in what they legislate for!
To get a nice single pulse from this laser, You will want a 30uF capacitor charged somewhere from 800 to 1200V with an inductor to shape the pulse
Les, when you make an air breakdown please remember, that the plasma is opaque to the IR/Green and half of the beam is actually gets reflectected from it (you can even see that the beam gets truncated). Also this reflection if gets amplified by the medium can damage the laser.
Critical plasma density (the one that reflects the radiation of wavelength "L") is proportional to L^-2, so IR typically reflects, while UV does not. a fully ionized air is ~2.5*10^19 electrons/cm^3.
Every time I hear about megawatt lasers it reminds me of Real Genius.
A truly iconic film!
reminds me of aligning six 30 cm diameter Nd:Yag beams in the lab where I did part of my PhD. Temporal alignment was also super important- so that involved delay lines and streak camera's. All combined they produced >6TW pulses and a very loud BANG when the laser fired.
Nice! I would have loved to have seen that!
I once attended an open day at the Harwell site in the UK and got to see the Vulcan petawatt laser, that was impressive - but being an open day it wasn't operational... The target vacuum chamber was large enough to enter for setting up experiments, and its inside was entirely coated in copper sputtered from the larget back-stop!!
@@MarkTillotson Yes our team collaborated with the Vulcan team, and our laser setup was similar and we exchanged a lot, but we were in a different location.
Try shining it through a KTP. You can remove the gunk off the flash lamp with dilute hydrochloric acid. Just rinse it off and clean with some alcohol before reassembly. Another thing you can do is put the q switch in at an angle and get highly polarized pulses out. The angle would be brewster's angle for halfmium oxide rather than YAG due to the antireflective coatings. A very inexpensive goggle set for YAG are surplus military SPECS, the green ones. They also have brown ones that cover NIR laser diodes.❤
Impressive work. I'm not sure about the losses and scattering of the joule meter? this might effect the reflected light back at the photosensor. Thus you will be getting a not very accurate result of the pulse duration? Also, I wonder if such laser can be used to evaporate materials on surfaces like a sputtering system.
2:06 good point. I knew that ruby lasers often had the actual polished surface of the ruby rod coated at one end 99.99999% reflective, and ~90%.at the emitting end.
Yep. You can buy YAG rods on AliExpress that are coated on both ends.
I got my hands on a few industrial Nd:YAG lasers i need to refurbish and get running, and this was what i needed to understand them better. 1x 20w and 2x 75 watt, hundreds of pounds, scary monsters for sure!
Nice! I'm glad this was useful!
Thanks that would be great. I have the laser head but would like to build a power supply for it
ok, i subscribed. not sure how i'm only seeing this channel now.
Thanks! Yeah, I am at the mercy of the algorithm!
on a side note, the corroded casing is actually aluminium magnesium die-cast alloy. low alloy aluminium is quite corrosion resistant. relatively high magnesium content in die cast "aluminium" improves casting properties, but practically remove aluminium's corrosion resistance to water.
I'd say use ethanol or similar for coolant. alternatively can add inhibitors, just not sure what is available commercially
Thanks. CO2 laser coolant will probably suppress corrosion and mould. I will have to look up the datasheet. I see later models of these lasers use machined billet Aluminum so they are undoubtedly more robust. Scored another on eBay for parts 😉
If I covered my stuff with high reflective mirrors would that essentially shield my stuff from DEW?
Hi man, just found your content and its really cool. I am wondering if there is a chance you could make a video about new flashlights that do not use LED diodes as a light source but LED diodes, laser excited phosphor diode? Particularly I am interested in science behind those diodes.
Also, I have an old laser tube from 150W CO2 laser, it has some cracks inside on a cooling lines, cant be fixed but I was wondering if anything can be done with "rubi" rod inside, it has a 150cm long pink-ish "lasering" rod inside, I call it rubi rod :D
16:34 nice is right! ive always wanted one of those rust stripping or tattoo removing lasers.. not because i have rust or tattos to remove, i just think it would be cool to have a powerful laser like that. i would make toast with it, or depending on the output, possibly a grilled chese, idk.
Fantastic! I just scored a newer model of one of these tattoo lasers a few days ago and am still awaiting its arrival in post sometime later this week. You can imagine my surprise and excitement when I see your video pop up today detailing its refurbishment and conversion to a proper benchtop unit! Wonderful!
P.s. finding 1" newport kinematic mounts and 4-sided sealable cuvettes has been my bane for weeks. Do you know of any consistent hobbyist-friendly sources that don't break the bank? I have a feeling I'll be scanning ebay for quite some time waiting for the mounts to show up.
Great!
Yeah mirror mounts show up at decent prices, occasionally. Look for MM1, or MM-1 for the little Newport mounts. To get bargains, look for scrap optical assemblies. Some of the cheap little CO2 Laser engraver mirror mounts look adequate as well.
Don't forget Laser safety glasses when you are using these things.
@@LesLaboratory Absolutely! I have a new pair of wrap-around 190-540 + 800-1700 blocking OD5+ goggles on the way. Wouldn't dream of powering it up without them. Nd:YAG is new to me but not high power lasers; I'm also a 4HV member from over a decade ago hehe.
A really great way to clean all those small metal parts is an ultrasonic cleaner. You can use water and a few drops of dish soap and it will knock off all that gack.
Wow this is beyond me. But interesting nonetheless. Thank you
FYI ive found that the calcium buildup (or whatever it is) is easily removed by soaking the parts in white vinegar and baking soda then brushing. (Obviously test a small area first ensure that the part is not going react badly)
Interresting stuff.
The 5 pulses you showed on the scope, why are the timing between them different for the first 3 and last 2?
This is because of the flash profile of the lamp, and the fluorescence lifetime of the Nd:YAG rod. I put a post up in the community section showing the output non-Q-Switched. If you look at the curve on that trace, it suddenly becomes clear where the odd spacing comes from. The first two pulses are close together, as they are at the peak of the pumping.
Good work, man and an interesting topic. I noted that you bleeding resistor got burned in the HV supply :)
Thanks! Yeah that's just something I throw on the output when I'm finished so it can't be inadvertently powered up! The burning is a feature 🤣
Be great if u could increase the pulse rate so looked like it was running continuously. Add more tuhes around rod and light simultaneously.
I reckon 10Hz is possible out of this with water cooling. Beyond that, problems await. Still, anything is possible!
if you trigger the flashlamp outside of the reflective housing would it be bright enough to blind somone like a flashbang?
Absolutely. The flash itself is an optical hazard, and is bright enough to bleach dark materials, and ignite steel wool.
Awesome, it seams you need some kind of 32 bit MCU to control the power supply or would the lamp not be able to be pulsed?
What an awesome video! I'm currently in the process of building my own yag assembly. Got an awesome deal on a 5x101.6mm 1% rod and I havent had success yet, but im trying! Also, I dont think you mentioned it in the video but are you using a film cap for your capacitor? I believe my failure has been in using electrolytics 😵💫 Thank you for posting this, you got a heck of a deal too!
Thanks! I picked up a 100uF 1.4kV pulse cap from AliExpress. Electrolytics should work, but you may have to tweak inductances etc, as they will discharge more slowly than film caps.
And this is why I don't experiement with lasers. Amazing detailed work and explination. Way beyond my understanding but enjoyable to watch.
Glad you enjoyed it!
Sweet. I'm always impressed how small these powerful lasers are. I wonder what the M² of a laser like this is, if it's at all usable as a beam, or if one is better off just relay imaging the crystal face through any downstream assembly.
Did you have a chance to measure Shot noise of this thing?
:-) Yeah, they are extraordinarily powerful for their size. Its hard to tell beam quality from vaporizing black paper, but I don't imagine it is very pretty.
I have not performed in-depth measurements, yet, and measuring shot noise at the moment would be difficult as it stands, as this thing is still rough. There is time though...
@@LesLaboratory haha my bet for the M2 is upwards of 20. Probably best to relay image into nonlinear Crystals to avoid rings and hot spots in the profile.
My daily life has become hunting down shot noise, so that's the first thing always coming to mind with these pulsed lasers haha.
does that power supply supply the trigger voltage to fire the laser? IS it home made and do you have any detail on the trigger part as in what voltage and how you add it to the 800 or so volts
Hi, yes, it has an in built trigger transformer, which superimposes a few kV at high frequency on the 800v power rail. There seems to be some interest in the electronics side of things so I may do a mini series on HV stuff.
you can modulate up to about 0.5MHz of so with the AOTF I have. Beyond that noise is a real problem. I have not checked of there is any polarization effect.
1.55. it may be unplugged, AND on someone else's bench, but i still have a brief urge to reach for my laser goggles!
The fact that you can get such a respectable output from a relatively crude cavity makes me wonder what sort of output i may be able to get out of the medical head that's been waiting for attention for some time!
Im starting to thinkbyou could Lase a telegraph pole if you hit it hard enough! Oooh, sounds nice! Any specs?
would this be possible to be combined with the spectroscope video you did to analyze metal? Units available for this purpose are very very pricey. Basically they use an electric arc and a spectroscope to do what I would bet your projects would do with correct software?
Yes. What you are talking about is Laser Induced Breakdown Spectroscopy (LIBS). If I recall, the trick is gating the camera to capture the afterglow (the initial plasma flash is broad band light). After that it should just be a software problem.
I think you could produce a product that would appeal to just about every junk man in the USA. Current units cost 15-50 K! I was thinking mini plasma machine but laser would be totally clean.
@@LesLaboratory
Btw did you measure the pulse width and timing of the output without the q-switch in? I'm curious if it is a much longer single pulse - if so it might make a cost effective modification to convert a tattoo laser to being appropriate for laser hair removal, which typically uses diode pumped YAG for wider pulses better suited for frying follicles. New hand-units are available for only $100 from china making this a very inexpensive massive upgrade for someone actually using it for aesthetician duties if the pulse width is right.
I did not, but it likely become a video topic. Without a Q-switch, you don't get a nice long pulse out of flashlamp pumped Lasers. Instead the "pulse" contains a train of spikes (aptly called "spiking"). It's an interesting phenomenon.
I suppose it could be put to use in the application you describe, but it would be fun getting the FDA to approve it!
Here is a screenshot: www.youtube.com/@LesLaboratory/community
Wow! It possible to use for recording hologramms
It may be possible with modification. The SSY-1 YAG's could be modified with external optics (etalon, brewster plate etc). It would be an interesting thing to explore.
19:45 Look at the roasted resistor 🤓
Could your power supply not be designed with e.g. a variable capacitor and variable inductor so that you can vary the duration of the pulse forming network? Very nice power supply by the way!
Thanks! As far as I know, nobody builds capacitors of this size as variable capacitors. Variable capacitors are normally just a few picofarads, and the high voltage ones are huge. If you wanted to make a truly universal supply, you could use multiple capacitors that you can switch in and out, and have taps of various inductances on the inductor itself.
One end of the cavity had more corrosion because the "gun" was probably stored on the machine one end up in a "holster" if that makes sense.
That makes sense. I recon the scorch marks in the cavityvis due to the Laser being run without water at some point as well.
Dissolved solids in the water, primarily calcium carbonate, will separate from the water when heated, and intensifies corrosion on metals. While the pump is going, whatever calcium that precipitated out is being moved around with the water, going through the machine and pump, but after operation you'll have heat soak as the unit doesn't immediately cool off when you stop using it. Chances are the machine had no post flow timer for the water pump, so that water was stuck in the cavity getting hotter and hotter with nowhere to go, allowing the calcium to precipitate to one end while being stored. Doing it once or twice isn't a big deal, but doing the same thing hundreds or thousands of times out of habit or convenience will eventually add up. Even with purified and deionized water it'll still happen, you can't completely remove TDS from water, but it would take way more time to build up than the unit itself will be functional.
shouldn't the cavity reflector be elliptical, or something close to that due to the thickness of the Nd:YAG and flash tube?
For diffuse reflectors, there is no need for an elliptical geometry as there are no focal points. The reflector surface is white, probably Barium Sulphate or some other highly reflective material. Most modern lasers employ close coupled diffuse cavity reflectors. There are very efficient, and evenly illuminate the Laser rod, with no hot spots.
how important is the q-switch? how does the laser behave without it?
Without it you get a long pulse, more suitable for ablation or welding. There is a post about it on the community page.
I had a Nd:YAG laser years ago but never got it to work because I was unable to get a suitable HV supply to operate its flashlamp. 😞
You can always build one, but do be careful they pack quite a punch!
Can't wait to see that Nd:Ce:YAG rod lasing! Any chance you'll be getting a Ruby or Alexandrite rod to complete the set?
Already have a couple of Ruby Rods awaiting a project or two! I must get hold of some Alexandrite, I have started seeing them on Chinese sites...
Love it ! What did that resistor do to deserve being strapped across the output haha ! what ever it did it looks like it's had enough....cheers.
Ha! I just chuck that on there when I'm done in case I accidentally power it up without stopping and thinking first! The smoke say's "You didn't do your checks Les!" :-D
I suppose you could try some basic libs spectroscopy with that. There are a few videos on TH-cam of others using the same cheap tattoo removal lasers for it.
Yeah LIBS! I saw that video a while back. That would be challenging but very cool.
@@LesLaboratory The main difficulty is getting the timing right. If you can get the CCD of your spectrometer to work with an external trigger (like x uS after the spike from a fast photodiode), it should work?
@@TheTablet314 That's how I figure it. Some cameras can be externally gated and they may well do.
Also you will want a nir pass filter that can exclude the lamp light but pass the beam. Other than that use the laser pulse itself as the optical trigger for the spectrometer.
@@LesLaboratory +1 on the LIBS. My Leica rep has been trying to sell me on one of their LIBS systems for a while but it's beyond my price range. Would love to see what you can come up with on the DIY front.
The movie "Real Genius" brought me here 😂
More info on the Pockels cell and Kerr effect please.
It will come! I'm building a system to grow large crystals for tis kind of stuff!
@@LesLaboratory I knew about the Kerr effect, bit a Pockels cell - never ever heard of them.
Interesting. Something to look forward to. :-)
You must be the luckiest guy in town! I wonder how often this kind of deal pop’s up on eBay. :)
you can buy the new tatoo machines for $500, so it's not that hard to get one!
Wow. . . . . you've got a big brain.
I was wondering, would it be possible to modify a laser like this to be diode pumped?
Possibly. Normally for Diode pumped Nd:YAG, you would use a rod with a lower doping, level. But Modern diodes are cheap, and if you are willing to take a hit on efficiency, I suppose it could be diode pumped.
So the Q switch is at that back, and blocks the rear mirror, I'd assumed they were at the front, and changed from reflective build up to release
I noticed that , too, and then I had to think about it a little, so the beam goes back and forward so many times and gets the crystals atoms all pumped up to a certain level and then the Q switch allows all light through giving the final pass the energy to invert all the atoms to dump the photons, population inversion, this is just a guess and probably a bit off...On another completely unrelated thing, here in N.Z. any lasers over 5 m.W. are not allowed in laser pointers due to too many idiots pointing them at planes etc...I saw one advertised on a local Trade site, it CLAIMED to be less than 5 m.W. but I had seen the same thing sold previously and it was 200 m.W. green, it was cheap and I purchased it, and sure enough , I'm not sure how many milliwatts it is, but it sends out a solid brilliantly bright green beam at night, quite handy for pointing out stars when I drag out my 8 inch Dob. reflector .
The thing that I hate about channels like this, is that they make me want to dive into the subject matter myself…but I only learn by doing, which means every hobby/thread I chase costs money I don’t have 🤣
I don’t even like money, and I gotta work every day just to feed myself lol. Can’t spend it on broken tattoo lasers and all the only random shit necessary to weaponize curiosity 😂
Styros brother. Bet they fight alot
Definitely new to this, but I thought I had a vague understanding of lasers from a physics/optics sense, and frankly am at a complete loss as how this can function correctly...
Isn't the point of the two mirrors at the ends of the tube not only to align the reflections into a beam (thus your clever alignment procedure shining another visible laser in) but *also* to match some integer multiple of the wavelength so the beam will all be in-phase?
And, isn't the same necessary for the "black crystal"?
It's been a while since I studied this, but IIRC the laser gain isn't at a single precise frequency, but a curve with certain bands of high gain. The laser will lase at any frequency with sufficient gain (and likely at multiple close-together frequencies) so unless you are going for an extremely precise/stable wavelength the mirror spacing doesn't matter. You're right that the highest gain will be at wavelengths where constructive interference occurs, but the difference between these "available wavelengths" is a tiny fraction of a nm with a cavity this long, so well within the band of high gain around 1064 nm.
The Q-switch (black crystal) should be antireflection coated so will just act as a lengthening of the cavity due to higher refractive index.
This laser is built for raw output power at minimum cost, so they don't care about the precise output frequency or maximising efficiency.
I think the mirror distance will influence the laser modes. So yeah.
Ah, you are referring to longitudinal modes. In many lasers many such longitudinal modes will Lase in the cavity. Lasers like this are highly multimode, and barely care about optical quality never mind modes. You will be surprised at what will Lase and what will not.
@@laserdancool.
What was the beefiest Laser you were able to use?
(I have to say, this laser looks WAY simpler than the laser at work. And ist also a "little bit" weaker than the one at work)
I think Styropyro did some experiements with a laser that looked very much like that.
He did. Lucky for him he got the power supply with it as well (those are quite expensive).
@@LesLaboratory Oh yeah, that huge case on wheels, I remember now. Guess the laser itself isn't that big of an investment.
i have a question: do you think you can melt Al2O3 with 5% Cr2O3 with a laser? (2000°C, Cr2O3 is green,Al2O3 is wihte)
It doesn't really melt, it vaporizes. It is capable of vaporizing and marking almost any material including ceramics, especially if focussed to a point.
this design seems like converting normal light to laser... i was wondering how it could be possible to create lasers from standard spotlights but newer seen an experiment with that... but theorethically its posible to charge anough light with good enough reflectors to align them to correct trajectory then mae it laser... :P that could find lots of areas to use.. ie use this to convert sunliht directly to lasers... but this charge sensitive semi reflectors mostlikely wont work with that... may be a transistor gate like logic controlled semi reflectors can do the job... liquid crystalls allready do this but they are not capable to withstand high temps nor high charges i guess...
I once saw a YAG laser head on eBay that was pumped with a halogen floodlight bulb! I wish I had bought the thing to play around with it!
Could one of these tattoo removal lasers be modified for pulse holography?
Possibly. It would need additional optics, a polarizing element, an etalon and a means of frequency doubling. It would be an interesting modification!
@@LesLaboratory At those power levels and pulse durations you wouldn't have to worry about stability. Is the cavity folded? Maybe you could add an etalon and Brewster's window in the area where the power was dispersed several square centimeters.
cant believe they just ran tap water through it...
0:55 I'm I the only one who tried to move sideway and feel uncomfortable when the laser was aim directly at my eyes?
Great video, but don't point such high power laser on my direction, even a broken one!
so can you use this to etch fused silica to store data
UV would be better, but then there are other more suitable materials than fused silica for data storage.
@@LesLaboratory Remember no one knows what was in the library of Alexandria and no one will remember our literature and art when something fails as it's all going electronic. While it may sound weird people 2,000 years from now may thank you for working out how to shove a lot of readable data onto quartz plates by using cheap tatoo removers and a microscope that we can build at home.
Styropyro ruined his camera with this kind of laser, so be careful, with your eyes and camera. Also, the Patreon crowd seems to grow... Huygens Optics also started with a single Patreon, the last video shows it had grown to 88 supporters.
Also, you could probably nickel plate the inside of the reflector chamber.
I did too back in the day, broke a camera with a dye Laser. When I filmed the q-switched shot in this video, I strapped a spare pair of safety glasses over the camera lens. I take no chances!
Yep, its growing! Thanks for the encouragement!
I could, but these cavities are supposed to have diffuse reflectors. It looks like compacted Barium Sulphate. I have some somewhere...
At some level you will ruin many cameras, if they're not shielded.
And if the laser beam is strong enough, it even may damage people standing next to the beam.
@@ElektrischInkorrektI think he is aware of the risks 😂
is it possible to convert it to remove rust from metal?
Yes, it will remove rust from metal.
So for a novice a mega watt sounds like it would vaporise a car! I see 5mw lasers on eBay and the like.
Is it producing a magawatt for a fraction of a second? Or does it produce 1 MW per hour?
Maybe just point me at a basics video.
Thanks
I should probably do a video on the fundamentals. So this is 1 Megawatt in just a few tens of nanoseconds, which is enough to vaporize the surface at least, of any material.
@@LesLaboratory wow , scary stuff! Even the psu was scary , I do electronics but that is a beast😮
glad to see you protected the firing switch . Nice work.
I didn't even know Nd Ce YAG was an actual thing. Why? Ce absorbing UV and doing an excitation transfer thing to the Nd?
Precisely! Because of this mechanism, manufacturers claim an increase in efficiency of about 30+%, enhanced UV stability and they also reckon you can run them air cooled at high repetition rates.
@@LesLaboratory nice!
Can I burn holes through Steel with it?
Maybe, I have not tried it. I suspect the Q-switch would have to be removed to burn small holes in thin (razor blade thin) steel.
Awesome video! - How do you test pulse forming networks generall, without, say, risking the lamp? Just short it dead?
A load resistor
I tested with a lamp. They are not terribly expensive from China, and if you do the calculations right it should be fine.
There are calculators on repairfaq.org where you can plug in values for capacitance, flash duration etc and they will calculate the inductor. Some manufacturers of lamps used to provide calculators for wall loading, de-rating etc, but datasheets are fine.
hi plz the schematic of the HV power supply ... thank you
mill and polish out the cavity and ends, then nickle plate.
Good idea! I will have to try plating!
Woah no way, I own one of these I scored off of ebay for dirt cheap ages ago but have yet to do anything with it. Wanted to make sure I had a better understanding before messing with high powered pulsed lasers.
Way! Please do make sure you invest in some proper Laser safetly glasses though, and mind the high energy capacitors! Othe than that, it is a very rewarding build, with great possibilities!
@@LesLaboratory absolutely, I already have all the parts to make a simple TEA laser. So I plan on starting with that and going up from there. But all on hold while I figure out the worst case scenario power output to make sure I select the proper OD glasses.
If we can hit 5Mw or larger with this sort of tech, do we really need a 1MW continuous beam to shoot missiles out of the sky, even hypersonic. Why not get a 10MW to 20MW qswitch shot.. or is the distance of the beam just WAY too short at that power to be effective let alone reach/burn through a missile?
1 MW is fun and all, and will vaporize almost anything, but only to shallow depth. To shoot down a missile, CW Lasers are a better choice. You would be looking at 50kW plus, and a target tracking system. Such systems are being field tested by Raytheon I believe.
I'm really surprised that the internal reflecting cavity isn't elliptical. An ellipse should be preferable with the lamp at one focal point and the rod at the other. Anything else will result in a non uniform distribution of light around the circumference of the rod.
For a specular reflector, for example aluminized or gold plated, yes and ellipse or other focusing shape is required. For diffuse reflectors like this, focusing won't work. The aim is to close couple the light and the diffuse surface ensures even illumination of the rod. The material used, often Barium sulphate (used in the world's whitest paint) has a reflectivity of more than 98%, more even than polished aluminium.
I listened to how this laser works twice. I still do not understand how I would build one out of electronic parts however, shucks