Marco Reps - 2023-12-12
PCBWays Christmas Activity https://www.pcbway.com/activity/christmas2023.html Accurate & Affordable Multimeters: https://www.welectron.com/Handheld 5% coupon code: marcoreps5 Mark-10 precision Torque & Force sensors https://mark-10.com/ R&S Next generation oscilloscope https://www.rohde-schwarz.com/de/produkte/messtechnik/oszilloskope/rs-mxo-4-oszilloskop_63493-1164992.html More from me: https://www.patreon.com/marcoreps Resources: Fabian https://twitter.com/voigtvision his OSH light sheet microscope http://mesospim.org/ Photo source https://microscopy.berkeley.edu/tlm/2P/index.html Little Bee B1 OSH Current Probe https://github.com/westonb/little-bee-B1/ Referenced YouTube Videos: The Amazing Microscopic World https://www.youtube.com/watch?v=qaElp0M3NZw fluorescence and confocal microscopies https://www.youtube.com/watch?v=BYwHLhgP1qI Mikroskopie jenseits optischer Grenzen https://www.youtube.com/watch?v=q-CMuaBlSQg Introduction to Confocal Microscopy https://www.youtube.com/watch?v=vn6app6XuII Killer T cell attacking cancer https://www.youtube.com/watch?v=jgJKaP0Sj5U Two-Photon Microscopy from Laser Quantum https://www.youtube.com/watch?v=EoW-7-orgyw Nano-scale 3D-printing https://www.youtube.com/watch?v=mdup3w7DCZE Green mega-laser shines over Stuttgart https://www.youtube.com/watch?v=5VtZo5JYr3I 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
Neighbors: "There it is again: VERY strange brilliant light emissions and maniacal laughter..."
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
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.
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
OMG! What a glorious score!
Don't look Les !! your jealousy will turn you green !
@@andymouse too late! Can't...look...away...from...screen...
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!
27:55 Pronunciation was spot on! You made me laugh really good Repson, thank you for that! 😊😊😊
Thx PCBWay for sponsoring such great content🎉
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%
Those interference patterns (?) at full power are beautiful and terrifying!
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.
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 YouTube. 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.
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.
8:22 Wow, the cooling water temperature is displayed with two decimal places of degrees celcius. Welcome to Switzerland!
Coherent is a US company.
That was an amazing video, thank you for this
You would make a great evil villain, my friend. You have the voice and everything! Love your videos.
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.
Man, I love your videos. Great information, sense of humor, and inspiration.
Happy holidays!
Can confirm, the mode locking "bump" is sometimes needed. Good old ti saph
Stay safe, Mr. Reps. Always impressed by your thorough attention to the details of whatever interesting subject you might explore.
Fascinating! I realize I can't even grasp the level of knowledge that you have. Congrats!
i stopped breathing when he opened the head 😂
I love any and all Coherent and Lumonics gear... Great acquisition!!
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
“Lap-a-FAP” deserves a Pulitzer!
This is awesome! Thanks for sharing.
There's a whole lot of multidisciplinary physics and magic going on in this video. Mesmerizing! Don't look into laser with remaining eye.
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.
Happy holidays, madman.
so glad I found your channel. so interesting and funny
Love Brymen. <3 shot of your shop from outside with it running and the speckled appearance of your hands is both terrifying and awesome :-D
Very impressive!
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.
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 work in microscopy field and never really new the point of the two photon microscopy, that was an amazing explanation!
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...
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.
Awesome content
Great video.
I spent one year with the Verdi, the clicky dial causes me flashbacks :D
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.
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!
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.
I used to do it support for a two photon confocal microscopy lab, that laser sure looks familiar 👍
@mikeselectricstuff - 2023-12-12
Lemo connectors used internally where nobody will even see them - definitely a sign of something built with minimal regard to cost!
@brentwheelock8297 - 2023-12-14
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.
@maxhouseman3129 - 2023-12-14
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.
@TheTablet314 - 2023-12-14
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
@universeisundernoobligatio3283 - 2023-12-14
Better to use MIL-DTL-38999, Series I LJT, II JT, III TV, HD connecters.
@maxhouseman3129 - 2023-12-15
@@universeisundernoobligatio3283 for sure 👍 🤣🤣🤣