Repair Attempt: Coherent Verdi Narrow Linewidth Green DPSS Laser
ฝัง
- เผยแพร่เมื่อ 29 พ.ค. 2024
- PCBWays Christmas Activity www.pcbway.com/activity/chris...
Accurate & Affordable Multimeters: www.welectron.com/Handheld
5% coupon code: marcoreps5
Mark-10 precision Torque & Force sensors mark-10.com/
R&S Next generation oscilloscope www.rohde-schwarz.com/de/prod...
More from me: / marcoreps
Resources:
Fabian / voigtvision
his OSH light sheet microscope mesospim.org/
Photo source microscopy.berkeley.edu/tlm/2...
Little Bee B1 OSH Current Probe github.com/westonb/little-bee...
Referenced TH-cam Videos:
The Amazing Microscopic World • The Amazing Microscopi...
fluorescence and confocal microscopies • fluorescence and confo...
Mikroskopie jenseits optischer Grenzen • STED - Mikroskopie jen...
Introduction to Confocal Microscopy • Introduction to Confoc...
Killer T cell attacking cancer • Killer T cell attackin...
Two-Photon Microscopy from Laser Quantum • Two-Photon Microscopy ...
Nano-scale 3D-printing • Castle on a pencil tip...
Green mega-laser shines over Stuttgart • Simply supernatural: G...
Timestamps:
00:00 Intro
01:36 Fluorescence microscopy
04:22 For Reps?
05:47 Verdi overview
08:24 Power conversion
12:22 Active noise filter
14:41 PCBWay
16:55 Backup battery
18:53 Service menu
20:56 Fapping
24:38 In the head
27:59 FAP replacement
30:16 Partial success!
31:40 Fine tuning
#laser #microscopy #repair - วิทยาศาสตร์และเทคโนโลยี
Lemo connectors used internally where nobody will even see them - definitely a sign of something built with minimal regard to cost!
I see your Lemo and raise gold plated Invar optics mounts around the V10 cavity. Those Permalign mounts heat up to the melting point of low temp solder when being adjusted; if not made of Invar the optic tends to crack from CTE mismatch. If not plated in gold, the solder won't stick. They cost Coherent more to manufacture than retail Thorlabs KS05 mounts would.
You should see what they did to the plastic Proteus flow meter for their ion lasers ... licensed the patent to swap plastic for CNC brass.
That’s because this modules get also sold single without this huge control case. You have then one production only for that modules and another for bigger systems. To produce the module with different connectors makes economically no sense.
I work for another big company on the market and we do it the same.
I have always wondered how their 'permalign' stuff works. But yeah, low temperature solder and invar mounts is certainly something.
As a sidenote: Does the low temp solder not have a CTE that pulls the optic away? @@brentwheelock8297
Better to use MIL-DTL-38999, Series I LJT, II JT, III TV, HD connecters.
@@universeisundernoobligatio3283 for sure 👍 🤣🤣🤣
Marco, just a little remark on your cooling fluid, don't know if it applies here. I hope you follow the Coherent Manual which type of water to use. I had a machine leaking through a shutter because the de-ionized water has eaten holes in the Aluminium block after months of running. The customers were not happy at all ...
Btw. I'm very impressed by your expertise, it looks like there's nothing you can't do or know in the electronics field.
Highly support that. We broke a 20k€ xray tube because the service technician just put deionized water in the cooling system. The tube manufacturer specified conductivity (reduces static build up in the tube), pH (proctects exposed parts), mineral content (in fact not "as low as possible") and some other things.
In the end they even supplied a recipe that basically read tap water plus some chemical (I think it was KOH) until the pH was at 9 and nothing else.
^^ This ^^ -- make sure you look at both the laser manual and the cooler manual if you have separate manuals for them. In the lab I work at, we use 5% ipa in water for our thermotek chillers, but we use tisapph lasers from a different manufacturer so ymmv.
Agree with everyone on this note. Pure water is a great solvent. Learned the same thing operating a pool, the water will leach minerals and metals if its not "neutralized" with the right Ph, alkalinity, and dissolved solids. Oh, and the right recipe is temperature dependent too.
We use OptiShield+ on all of our lasers.
@reps take this tip above all others, a machine running at half power is better than a machine that leaks
Neighbors: "There it is again: VERY strange brilliant light emissions and maniacal laughter..."
I’m glad the original owner thought to give this a new home on your bench, from where we can all learn something, rather than consign this to the dumpster.
Scrapped out isn't the dumpster. There's a lot of precious metals in high end electronics like that.
@@bobroberts8500 Of course. Anywhere I’ve worked, ‘the dumpster’ was the metaphorical term for ‘we don’t have an interest in or liability for what happens to it next’. No way this won’t one day be picked over for parts for reuse and recycle. At least I hope so.
There's something really beautiful about the design of these hyper-specialized tools, thanks for showcasing this one
The engineering and craftsmanship contained within. A beautiful thing.
“Lap-a-FAP” deserves a Pulitzer!
Ah yes, more esoteric electronics content!
If you ever worked with lasers in precission applications, you know that theres nothing esoteric about this but every bit of accuracy seen is needed
I'd guess the power goes down at high pump currents because something is misaligned slightly, but I can't see a kinematic mount in the main laser cavity. If you do have some kinematic adjustments in the laser cavity, hooking the power meter to one of your super DMMs and following the power/adjustment curve to it's maximum for each adjustment 2-500 times can make a big improvement.
Fyi, a cheap digital camera with the IR filter removed makes an ideal 808nm and 1064nm viewer. It's an excellent safety tool. (know where EVERY stray beam goes!)
The speckle pattern is nice and steady. Though if you really want a quick n cheap way to see how good the spectrum is, get an Iodine vapor cell. The contrast between tuned to an absorption line and off a line is a nice simple way to measure spectral purity. I'd expect Etalon temperature and LDO temp to be your main tuning parameters. (though pump power and everything else will effect it to)
Last, be aware that a lot of chillers and TEC cooler control loops are highly sensitive to ambient temperature. If you ever see the device temperature go down while ambient temps go up, it has a faulty feedback sensor design.
I "tamed" a DPSS green laser like this in my Graduate work.
Thank you for the hints! Yes, most optics in the cavity seem to be soldered. I think I'll live with 7-8W for now rather than taking any risks in there
31:20 Nice Laser speckles you made. Im working with a green LASER of a magnitude less power (~3 mW) in my lab, doing ESPI (electronic speckle pattern interferometry). Its an interesting topic worth looking into in my mind. You can extract micrometer height differences of a 2D plane through the phase information stored in the intensity of an image
Sounds great! That goes into my TODO list
Thought this was optical coherence tomography until some online reading ... sounds more like shearography. Interesting.
Can you explain what causes the speckles simply? I am a fan of physics, but have minimal formal education on it.
Thanks!
10:32 - emitter follower from oscillator to current sense input performs what is called "slope compensation", technique used in current-mode control PWM converters to improve stability at duty cycles of >50%
Can confirm, the mode locking "bump" is sometimes needed. Good old ti saph
OMG! What a glorious score!
Don't look Les !! your jealousy will turn you green !
@@andymouse too late! Can't...look...away...from...screen...
There's a whole lot of multidisciplinary physics and magic going on in this video. Mesmerizing! Don't look into laser with remaining eye.
PLCC sockets are known to go bad over time and are often a source of very erratic problems. The spring pressure in those sockets is pretty low because otherwise the sidewalls would deform to much. Removing the PLCC chip and cleaning the socket and chip will get those going again.
Mr. Marco, I wonder almost every day when you will come out with your next video. Your work is by a magnitude better than other “experts” on TH-cam. I often re-watch your videos in the middle of the night when my tiny infant wakes me up. Your sense of humor is great and I laugh loud. My wife of course says WTF is wrong with you? Then I hide my phone with your video and pretend I have no idea what she’s talking about. I’ve been following you for years but now that I’m out of parents’ basement, I can actually afford tools and set up a complete JBC lab. Can’t wait for your next project and try to replicate it. You seem to live in practical world.
27:55 Pronunciation was spot on! You made me laugh really good Repson, thank you for that! 😊😊😊
Thx PCBWay for sponsoring such great content🎉
Those interference patterns (?) at full power are beautiful and terrifying!
8:22 Wow, the cooling water temperature is displayed with two decimal places of degrees celcius. Welcome to Switzerland!
Coherent is a US company.
Awsome necromancy on this laser, 8W isnt too bad for something that was gonna be scrapped. Also as this is the narrow linewidth version you can use it for making holograms too.
i stopped breathing when he opened the head 😂
Please get a laser curtain for your windows to protect the outside ! With this kind of laser even diffuse reflexes can be dangerous.
Flying Schrodingers could or could not bump the head, and then could or could not end up in an airplane cockpit window via a reflection from an instrument transflective LCD backing. I'm sure he knew the risks, but it is a good idea to be better safe than sorry. His shots from outside looking in via the window were spectacular. The green goblin is somewhat of a scientist himself 💚
In our trade (automation) laser curtains is what we call anything that is used to detect the "presence" of a human. :))
If the reflection is actually diffuse, it’s only under 10 watts, that’s not enough to do damage to anything at more than a centimetre. Eyes won’t be damaged by such a reflection beyond maybe half a metre, not that I’d be within 5 metres without laser goggles, far more of there was even a small possibility of specular reflection. So long as he insures there’s no chance the laser can’t shine directly out of the window I don’t really see a problem, this would involve bolting it down and ensuring nothing reflective could end up in the beam path.
@@Scrogan "Eyes won’t be damaged by such a reflection beyond maybe half a metre"
That's a very bold statement. Do you have a source for that?
@@Scroganwhile this is generally true, its of course not a guarantee that there wont happen to be a reflective surface somewhere that isnt diffuse enough. you either point the laser at a diffuse and safe beamstop or you seal the room by lowering the blinds.
You would make a great evil villain, my friend. You have the voice and everything! Love your videos.
That image @5:10 literally jawdropping
It's worth noting that you can operate most Ti:Sa laser with just 5W of power just fine. As for mode-locking: There's lots and lots to say about of cavity alignment, but you'll eventually get there, don't give up.
Yea these Verdi's are quite reliable I have a few of those in my labs, but mine are air cooled, a peltier chiller is used to keep the head at a stable temperature, there should be a base plate for that.
Yes definitely! There should be normally a 7 cm block of aluminum below it and this is cooled by the peltier chiller (together with the mira). Already small temperature increases leed to thermal expansion and therefore to a misalignement of the cavity. You can easlily have 30% less power beacause you are some degrees of.
I have a Verdi riser block sitting in my barn now, would happily donate it to Marco if shipping a 30lb block of aluminum from Colorado to Stuttgart made any sense. They sure look pretty, but any 1 or 2cm thin lapped cool plate will work better. The added thermal mass of heated aluminum block takes time each morning to thermalize, which offsets alignment from pump to Ti:Sa. @@humwuuhu8433
I'm jealous of the Mira 900! I have two Verdis, but have so far not been able to track down a Mira in good condition. They're a great laser system, used to work with one from the early 90s that had been through multiple Verdis in its lifetime and still worked perfectly. Assuming you have the pump, it'll last forever.
The technology is way beyond my education but I did a double-take at your FAP driver visual at 6:39
I don’t know if everyone else is more mature than me so didn’t mention it, or if they were too busy looking at the box.
Great video, loved the humor, and may have learned something!
Thank you for showing this to us. Ideas for the power loss: the FAPs could be close to end of life and are drawing more power to deliver the needed output. At the upper end they may be generating more heat than the system can remove, throwing their wavelength off. Or there could be a small alignment error. I have found if the pump mode and cavity mode overlap are a little off, thermal lensing in the vanadate can cause the power to drop. I've been building a green DPSS for a while now and I see things like this when the power gets over about four watts of green.
Thank you for the suggestions! I think I will try some more cheap FAPs in both positions, but I don't feel sufficiently equipped to tweak things in the cavity (yet) Gonna have to live with 7-8W if there's something wrong in there
The lifetimes on the original pump diodes look ok-ish ~10k was the limit for the earlier ones. I agree with @BiranKPepin on the possible issue but think the pump wavelength stability of the replacement is the more likely issue. If you test in constant current mode then you can plot out power vs current graphs (532 nm output vs pump diode) that should be linear till you hit a roll off (some nonlinearity from the SHG). Pushing too far past saturation point of the system typically breaks something, try adjusting the pump diode temps up near the saturation point. Alternatively look at the output wavelength of some scattered light with a spectrometer, if you have one.
I usually end up just running these older systems in CC mode continuously, pretty much every one of them has the service mode enabled and its typically far more stable than the "constant power" mode. often lets you push a few extra thousands of hours out of the pumps too. The newer systems have the pump diodes in the head, far nicer. I would offer you more of the same as I have scrapped a number of these lasers over the years but the drive to Australia is a bit longer and my regulator would probably complain.
The weird transistor at 10:14 is used for slope compensation, it's an emitter follower that adds some of the RC oscillator ramp to the current sensor output to make it stable.
I thought this was a huygens optics video from the title! I love seeing stuff from my world show up on this channel, and all the imaging nerds here in the comments! Green DPSSs are always dying, and it's thrilling seeing you resurrect this one. If youre ever in the US in virginia, I have an ailing DPSS for you to look at :)
For clearing the loop of gunk, a vinegar wash is great at breaking up galvanic/biologic buildup on interior surfaces. Just dont leave the vinegar in there...
That was an amazing video, thank you for this
Just FYI you cannot determine the health of a timing belt by looking at it. I've seen plenty of timing belts that broke and still looked like they were brand new. Age and mileage alone determine when a timing belt needs to be replaced.
Stretch is the only good measurement. The fibers will stretch before failure daily reliabily
@@ionstorm66 I've been a professional mechanic for over 20 years and I've never heard of anybody using belt stretch as a way to determine when a timing belt needs to be replaced. Replace them on the schedule specified by the manufacturer. If you buy a car and don't know when the timing belt was last replaced go ahead and replace it.
Some engines use what’s called a stretch belt as well, to negate the use of a belt tensioner
Man, I love your videos. Great information, sense of humor, and inspiration.
Happy holidays!
This is awesome! Thanks for sharing.
I love any and all Coherent and Lumonics gear... Great acquisition!!
Happy holidays, madman.
Very impressive!
Stay safe, Mr. Reps. Always impressed by your thorough attention to the details of whatever interesting subject you might explore.
yoooo I'm a neuroscientist and when I saw "verdi laser" I was like "*that* verdi laser?" and well it was. Also modelock hype
so glad I found your channel. so interesting and funny
Love Brymen.
Fascinating! I realize I can't even grasp the level of knowledge that you have. Congrats!
Great video.
Awesome content
I spent one year with the Verdi, the clicky dial causes me flashbacks :D
I work in microscopy field and never really new the point of the two photon microscopy, that was an amazing explanation!
Plating with the pump diode fiber optics changes the modes and was a trick to make the laser behave better. On some designs used to zip tie them in place.
The high output power is probably due to IR to green conversion in the crystal. If the crystal starts overheating, its efficiency drops. Thus, the green power drops. If you can fine tune the crystal temperature, try lowering it? And maybe you reach a higher power. Tho, it is usually set to a sweat spot based on a beam size.
Correct; SHG conversion drops which adds to intracavity IR light and thermal lensing in the vanadate which further increases mode size at the SHG waist. Since the servo operates on green power, it's a cascade that rolls over quickly. V10 was the IR lensing limit. On the V18, a thermal lens is factored into the resonator design and you thus need to establish a strong lens to get green conversion.
Check FAP wavelength is 808nm and/or adjust diode temp to try finding a different order of the DFB grating. Otherwise 8W of Verdi TEM00 is plenty to modelock the Mira, it's the DPSS mode that really improved Ti:Sa pumping over ion lasers, 532nm is further from Ti:Sa absorption peak than 514 or 488nm.
You can use ordinary automotive water/antifreeze mix. It cools the laser diode mounting block. Those big gold boxes have TEC cooler modules inside that cool the pump diodes. The TEC modules in these are failure prone, but the FAP submidule inside is usually OK. The fix is to replace them and then use a simple radiator and a fan, they neglected thermal expansion and it causes the cooling crystals to crush at the torque used.
used to work with these once ❤
love that you are still getting texted about that laser driver, because i literally just got one of those modules and was tempted to text you ^^
i gain so much, what i like to call, 'Scale of Spectrum' (pun not intended) knowledge. finding out what limits electricity has, what limits circuit designs have, new concepts in the industry i would never otherwise find out about.. and so on. I get a better idea of the spectrum of all things involved in electronics. great vids man, i cant turn down watching ur vids when they come out.... just too juicy to miss
Yep.
what fun!
awesome!
As someone who knows just a little about electronics, this sounds like the turboencabultor video the whole time.
very interesting!
I used to do it support for a two photon confocal microscopy lab, that laser sure looks familiar 👍
That green beaty is burning my eyes even over youtube 😎
You are a wizard
Worked with a V12 before to pump a Coherent TiSa for exitation of Rubidium D line at finally 2.5 Watts output. Still more effecient than Argon Ion lasers as pump.
Very excited to see whats going under the hood of the Verdi 😊
oh wow! I made many parts for that laser!
Awesome! Electronics, optics...?
Damn!!! I live there!!!!
Nice !
Oh, hell. Ok. You get a thumbs-up for the F.A.P. joke. I feel so dirty. And so 12.
My laser Jedi master used to have 40w green laser mounted to cutting head. He rigged it up to cut metal sheets on a mill. Talk out about bright 😮. Even the reflections off the wall was to much. 😂
Well since my hobby is analog power supplies for valve ( vacuum tube ) stereo circuits . I found arcane for this a LOL moment . Fine video.
I love Switzerland, such a good idea. I’m glad it came up with it.
Nice, finally! :D
Thank you for the assistance 🫡
Looks like you awakened a Necron tomb world.
Hey Marco, I have a 150w YAG laser engraver with a dead or dieing pump diode , it's yours of you want it (south east UK )
Howdy from just outside Brighton !
Oooow, shiny new toys
How long did figuring out the repair take? I kind of wish we had a video of the process
It stood in my waiting room for over 2 years while I worked up the courage to work it. After moving it to the operating table, it was relatively quick, 1-2 weeks thanks to some valuable hints from Eric, Rowan and Ebi
Fascinating how your voice never changes... Maby think about changing modulation at some point 😁
Nooo! I know very little about electronics but listen to Marcoreps videos for the soething voice.
I think if his voice changed, it would be due to some serious outcome, like inadvertent black hole creation that will begin to eat the earth. Everything else is just chill.
I have never bothered messing with cavity alignment on a Verdi. They work till they break and at that point they are hardly worth fixing in the research world with the current gen Millennia lasers. That said its pretty rare the cavity breaks, usually the pumps, LBO or something electronic goes in them, as we have seen.
The Mira I have no experience with, much more use to the Tsunamis shown at 4:40. If you don't have a spectrometer, you can use the speckle pattern to check if you have it mode locked. The speckle disappears when the wavelength broadens. Get a decent isolator for the output if it doesn't have one built in otherwise it will never stay mode locked, they all hate external seeding. After that I expect nothing less than a homebrew autocorrelator to measure pulse profiles!
Looking for the speckle to disappear and avoiding back reflections are great advice, is there another source for GaP photodiodes now that Thor doesn't overnight them with Lab Snacks? Or how do you generate/isolate SHG for the autocorrelation?
The Verdi power rollover at 8W might also be fixed by adjusting the FAP temperature (I think there was a service menu for this); these are DFB pumps and need to be well centered at 808nm to minimize thermal lensing in vanadate.
I have found my kind of people! For sure, this is top notch advice.
@marco reps, The mode locking tip and the one about the isolation (esp that) are super valuable advice btw.
@@brentwheelock8297 A delay line and a thin sliver of BBO make a decent autocorrelator. A slow Si photodiode is enough, you can filter the pumps from the SHG with angle, focus the two inputs with a lens at a large angle into the BBO, SHG vector comes out straight (sum of k vectors, collinear operation). With very thin BBO and sub picosecond pulses it is very easy to be phase matched, bit of angle tuning but nothing like the critical response you have at longer pulse durations.
bringign back lapping old cpus and coolers, thsoe were the days
Marco vs Darth Vader lets go
I have personally observed this kind of runaway behaviour on two different 532nm pump lasers. Both were rather old and could not deliver their rated power any more (the spectra physics one even died when I was using it) so I'm not sure if it's indicative of a common issue or if it's just how they behave. One was a Verdi V8 or V10 (can't remember) and the other one was a Spectra-physics Millenia eV.
Other guess maybe it could be the ir pump that you haven't replaced that can't produce it's max rated power anymore and goes into runaway ?
Possible! I have read somewhere that modern FAPs can last 20k hours and more, whereas mine have supposedly only worked for 6k hours. Maybe it's because they are some of the oldest
crazy !!!!!
Reps looks straight-up super-villainous a 33:06. You've already got the accent, now you've got costume.
29:45 for a second I got scared that that thing was a new version of the blue brushless brutality beast
In a nutshell, is that beautiful scatter pattern reflecting on your walls entropy? How can you measure it?
27:18 😂 you’re the best
Dear Marco, how about a heads-up on the actual (working) condition of your laser? I (and others for sure :) ) share the same passion for otherworldly laser-power ;)
don't even want to know how much cost this :/ my old hobby 20years ago still love dpss lasers but after all of those years they are still expensive even low watage, real 100mw cost 200£ with tec coling i think this is still expensive after all those years
Me: Hi my names CC and I too suffer from MLAD (Manic Laser Acquisition Disorder).
Marco: Lasers! Need I say more?
Me: Nope you had me at L….
How does Indium compare to graphite sheet? They have great thermal conductivity and soft enough to conform most uneven surfaces.
I was thinking that Thermal Grizzly Liquid Metal would make a significant difference.
Used properly, indium sheets are ~an order of magnitude more conductive than graphite (on the same order as liquid metal). @BobHannent You probably wouldn't want to risk using liquid metal with equipment like this
hello, Thank you for the video. We have verdi 2 W laser. However, when we increase the power more than 0.01 W it shut down automatically. Do you have any idea what the issue is?
nice
how do you protect yourself and your eyes from these amounts of laser power, or even its reflections?
Goggles are rated for wavelength and optical density. Suitable goggles for a laser like this would have an optical density of 6 or higher. That reduces the light by a million times, but only for the narrow wavelength of the laser so you can still see fine through the goggles. For skin exposure, it's usually fine unless it's a direct beam strike or very short wavelengths (like UV).
@@BrianKPepin so it's basically like the color changer crystals in the device itself, but they convert it to heat vor example
blocks of gold:)
I snorted out loud at "lap a FAP"
11:12 IDK, kinda smart, make a different phone number for each part, so when customer calls, you just have to ask for shipping address and money transfer :D
from star wars to lord of the rings ... creating our own little Angmar, are we ? Will the evil wizardry never end, sigh ^^
goooooooo video brooooooo
Awesome to see the green phoenix rise from the ashes! I do hope 'fap lapping' doesn't become the next TikTok trend ;)
It'll be posted on his OnlyFans later ..
Big Scary Lazor!
I wasn't expecting to see a sticker
crazy
More! Powhahhhhh!!!!!