Experience with 50W chinese YAG modules?

[TCWilliamson]

Hello LPF,

So, I posted a while ago about a laserscope I purchased (I still have it, sitting at work under a Poly sheet, gathering dust) I realised, redoing a flash-pump controlled YAG system would be extremely expensive and I would need a lot of time to do so, plus a lot of experience.

So, I started looking back towards Diode based units, I've been idly looking on and off, and I've always seen these following things about, unsure of how trustworthy they are:

Chinese YAG modules

They pretty much just consist of a water cooled module with suitable 808nm diodes, arranged around a YAG crystal.

I recently found a video online of someone running these. (I've only actually found one person so far.. but they seemed to be having good success)
Has anyone else had experience with these units?

I understand these are somewhat in the realms of unspeakable occasionally, but I can assure that I am quite cautious, I have suitable laser goggles for any lasers I own and if going down this route, would buy a pair of 1064nm goggles to go with them.


I understand the mirrors and optics that go with these high power lasers are very expensive, I theorize that the mirrors I have from my Laser-scope might be perfect for this as they are matched in wavelength and power, however I would need to run some tests to check them over, or consult someone experienced with the laser-scopes already. I naturally have the Q-Switch and KTP crystal assembly from it too. Such a set up could be interesting to play with assembling in the long term.

I also find the cost difference curious between this and this

They also have matching power supplies, but I don't know if I should hold concern over them enough to want to make my own to reduce risk of the diodes being damaged... That said, if they can make a YAG set up, I'm sure they can do the PSUs.


BR,
Tom

 

[TCWilliamson]

I see it needs water cooling and a power supply, but is that 50W CW ?

It would likely have a good beam profile.

You are certainly correct. On all accounts.

 

[RedCowboy]

Yes and a used US unit cost more than that, it could be a good deal if that's what you want, I would like a high quality 50W beam but I am holding out for a used true fiber laser ( not fiber coupled ), still it's shorter than a CO2 glass tube.

What's it's rod pumped by ? Flash lamp or diodes ?

 

[TCWilliamson]

Yes and a used US unit cost more than that, it could be a good deal if that's what you want, I would like a high quality 50W beam but I am holding out for a used true fiber laser ( not fiber coupled ), still it's shorter than a CO2 glass tube.

What's it's rod pumped by ? Flash lamp or diodes ?

Ya can see on the links I gave, and I mentioned it in the first post, but yes, it's Diode pumped. :san:

I don't know how much money more I'd need to be saving for a fiber laser, but realistically, I figure it would be fun to make this into an assembly, a good learning project, and I'm curious how small one could make the whole module.

I'd be curious about dropping this into the laserscope assembly:

EDIT: Diagram fixed:

FYI, your diagram has a small error.

 

[RedCowboy]

It says diode pumped on the related results at the bottom of the page but not on the ad referenced, but I do see it now, looks like 360 watts in for 50 out so 310 watts to shed via liquid cooling is not that bad.

Odd how some have much higher shipping.

Depending on the wavelength produced there could be a markup to be made reselling on ebay, but this is true with many things, often people will pay more to get it fast when dealing with smaller items, but I wonder if these actually sell on ebay??

https://www.ebay.com/itm/GTPC-50S-l...d=152750718042&_trksid=p2047675.c100009.m1982

https://www.aliexpress.com/item/YAG...id=205a0bfc-2dcd-4f19-ac14-e0eb37969b43&tpp=1


But I digress, I have not worked with a laserscope assembly, but member Diachi should be able to offer some input, I am interested in the power and beam quality for the price. I would source and/or build my own power supply.

 

[diachi]

You are certainly correct. On all accounts.

Not really, just because it's diode pumped doesn't mean it'll automatically have good beam quality. Especially considering that those units are side pump, not end pumped. The beam quality is highly dependent on the cavity design.

I'd be curious about dropping this into the laserscope assembly:

You won't be able to just "drop it in", I can tell you that much.

There was a post on PL years back that talked about the possibility, there may be more recent discussion too. Here's the post:

Others have considered this too, but I haven't seen such a conversion done yet. By its nature, the optical relay will operate with a wide range of thermal lensing in the rod, so you may be able to use the same optical components. But I doubt you would be successful with a blind plug-and-play conversion. If you search for Laserscope patents by Kuizenga, you will learn about the design of the resonator including the typical 1064nm resonator power and 532nm conversion efficiency. I would not recommend attempting this conversion until you understand the design of the Z-fold resonator very well, because there are many factors to be considered.

Also, consider the cost of this conversion versus what is to be gained. Unless you have a very good source for surplus pump diodes, and you are competent to design your own pump chamber and diode driver, the Laserscope machine will be the cheapest component in your design. Though the electrical requirement will be reduced, the result is still physically very large, and the pump diodes, YAG rod, Q-switch all still require water cooling with a radiator or compressor (it is not economical to use TEC for such high power pump diodes). In my opinion, it is not worthwhile.

If the electrical requirement of the Laserscope machine is too much, I suggest you search for a more recent machine e.g. Laserscope Aura which is already diode-pumped. You can also consider Coherent Verdi, Spectra Physics Millenia or similar lasers, which have much better beam quality, but they are rare on the surplus market.

If you understand the design of the Z-fold resonator very well, and you are familiar with principles of optical design, and you have a lot of spare time, then you can build your own green machine based on any 1064nm laser. But if you place any value on your time, it becomes much cheaper to buy a machine which was green from birth.

If you have any more specific questions, I am pleased to help if I can.

Best regards,

weartronics

Full thread: https://www.photonlexicon.com/forums/archive/index.php/t-7605.html

You'd probably have an easier time building something from scratch using one of those Chinese YAG units. Although I'd start with something much smaller first.

 

[TCWilliamson]

Not really, just because it's diode pumped doesn't mean it'll automatically have good beam quality. Especially considering that those units are side pump, not end pumped. The beam quality is highly dependent on the cavity design.



You won't be able to just "drop it in", I can tell you that much.

There was a post on PL years back that talked about the possibility, there may be more recent discussion too. Here's the post:



Full thread: https://www.photonlexicon.com/forums/archive/index.php/t-7605.html

You'd probably have an easier time building something from scratch using one of those Chinese YAG units. Although I'd start with something much smaller first.

Ah yes, I came across that thread before too while researching. The main idea is yes, to build something from scratch. I don't know much-if-anything about the Z-Fold set up. I would be wondering if I can save myself some good money using the mirrors from it, I am not certain, but believe to a 'confident' extent, that I could probibly salvage at least a few of them for such a project?

Ultimately I need a 'cheap' set up to experiment with laser-cutting and sintering. I'm aware I could probibly buy a complete unit, but they cost significantly more. That may well be cheaper with the time factor included, but I would not learn nearly as much.

 

[CurtisOliver]

I second Diachi. You can’t just ‘drop’ one of these in and expect it to work. Have you tried assembling a low power dpss before? If not then don’t waste your time and money on this yet. We have many on here that work with dpss’s and realignment and it really isn’t as easy as it seems.

 

[TCWilliamson]

I second Diachi. You can’t just ‘drop’ one of these in and expect it to work. Have you tried assembling a low power dpss before? If not then don’t waste your time and money on this yet. We have many on here that work with dpss’s and realignment and it really isn’t as easy as it seems.

That was just one idea I had been considering, however if it's not quite that easy without major re-cal, I'm not loosing any sleep over it. I had figured that would be the case.

I haven't had a chance for assembling a low power system yet, no. But it seems many of the components are easier to come by at the 50W range, due to the number of Chinese engraving machines that are popping up. With the access to a nice selection of mirrors and lenses, plus a small power meter from the laserscope, one may think they could salvage -something- from it.

I'd love to put the laser parts to good use as I want to take out that HUGE 50A isolation transformer from the bottom for another project, but I'm holding off as if I can't do much with the laser, I might as well sell the whole unit together so as not to loose money.

I'm very much open to being guided in a direction.

 

[diachi]

I haven't had a chance for assembling a low power system yet, no. But it seems many of the components are easier to come by at the 50W range, due to the number of Chinese engraving machines that are popping up.

A Z-fold is not the place to start. Even if parts are easier to come by, such powerful/complex systems have many more hazards and there's much more that can go wrong with them.

 

[TCWilliamson]

A Z-fold is not the place to start. Even if parts are easier to come by, such powerful/complex systems have many more hazards and there's much more that can go wrong with them.

I am not stupid enough to argue with that. I am stupid enough to ask if I could set up a resonator using the existing parts from the system in a simple YAG assembly (with or without Q-switch)

Or would it be a very bad idea to take apart the Z-fold as it holds more value assembled in the way it does now, then the sum of it's parts if I needed to re-aquire them for a 'simple' YAG resonator.

 

[diachi]

I am not stupid enough to argue with that. I am stupid enough to ask if I could set up a resonator using the existing parts from the system in a simple YAG assembly (with or without Q-switch)

Or would it be a very bad idea to take apart the Z-fold as it holds more value assembled in the way it does now, then the sum of it's parts if I needed to re-aquire them for a 'simple' YAG resonator.

The resonator optics will only work with certain resonator configurations. Assuming your scope is using much the same resonator design as an 800 series then you've got at least 3 curved mirrors in there. SAM, RAM and OC, with a flat HR. Guessing the fold mirror before the HR is also flat.

You can't just throw a resonator together with any old optics in any configuration, resonator design can be fairly complicated.

 

[TCWilliamson]

The resonator optics will only work with certain resonator configurations. Assuming your scope is using much the same resonator design as an 800 series then you've got at least 3 curved mirrors in there. SAM, RAM and OC, with a flat HR. Guessing the fold mirror before the HR is also flat.

You can't just throw a resonator together with any old optics in any configuration, resonator design can be fairly complicated.

Indeed, well you can see my resonator design further up the thread where I've taken a picture of it an drawn out the beams to my knowledge.

I have the so called 'bible of solid state lasers' (Solid State Laser Engineering by W Koechner) but a good bit of it goes over my head, though I can grasp much of the principle concepts. I'm mostly self-taught. I work in motion control / electrical engineering.

I would very much like to progress with this project, or a similar enough one. I'm not foolish enough to go against all recommendations, but the reality is, that I do want to set up a 50W YAG 1064nm beam for a galvo and voice coil array to experiment with some engineering ideas I have.

I would also like to learn how to build a resonator regardless. Z-fold is obviously not a 'starting point' What would you recommend, I'm happy to all advice / education I can get.

 

[diachi]

If you're just going for 1064nm there's no reason to build a Z-fold. A simple linear resonator is enough. Not sure if your scope has it, but as you can see on the diagram I posted there's a "wavelength select" mirror which is inserted into the cavity. That mirror essentially turns the cavity into a linear cavity, removing the SAM/RAM/KTP/OC and as a result switching over to 1064nm output.

This page has a lot of good information on some smaller DIY DPSS systems. https://www.repairfaq.org/sam/lasercds.htm

 

[TCWilliamson]

If you're just going for 1064nm there's no reason to build a Z-fold. A simple linear resonator is enough. Not sure if your scope has it, but as you can see on the diagram I posted there's a "wavelength select" mirror which is inserted into the cavity. That mirror essentially turns the cavity into a linear cavity, removing the SAM/RAM/KTP/OC and as a result switching over to 1064nm output.

This page has a lot of good information on some smaller DIY DPSS systems. https://www.repairfaq.org/sam/lasercds.htm

Hello,

No, my scope doesn't have that, you can see my scope here:

https://i.imgur.com/KScAYu6.jpg

So the likelihood is that there is nothing in my laser-scope, short of maybe 1 mirror and the Q-Switch possibly, that would be useful in me building a linear cavity?

If you really want much higher power (e.g., 3 W) and are willing to spend a few thousand dollars per unit you can buy a pair of crystals, Nd:YVO4, and KTP from ITI Electro-Optics for about $900 you can also buy a 20 W 808 nm laser diode for about $400 from IMC Microphotonics Company (now CEO Laser, part of Northrup Grumman). Go to the Products page for information (but no prices, unfortunately). Grand total: $1,300. Unfortunately, JUST THE PARTS, in small OEM quantities (several tens of units) to build a complete laser in this power range total just over $8,000. You also have laser diode drive to worry about, temperature control, precision mounts, optics, laser diode beam conditioning, to mention a few other problems. This doesn't include capital equipment like a laser beam analyzer, wave meter, temperature probes, milling machine to make up the components (OK, that one can be farmed out to a machine shop), ESD-safe soldering iron (PLEASE spend the money to get one - your laser diodes will thank you). If you do want to do this, it IS doable and there are manufacturers doing it. But, there is a reason why the systems cost so much. I would suggest a more modest goal, I.e., a few hundred milliwatts. This would be a much more realistic project, and would fall into a more reasonable price range.

Amazing how far prices have dropped these days for many of the components for higher power Lasers, especially now how China is getting in on High tech manufacturing.

 

[diachi]

Hello,

No, my scope doesn't have that, you can see my scope here:

https://i.imgur.com/KScAYu6.jpg

So the likelihood is that there is nothing in my laser-scope, short of maybe 1 mirror and the Q-Switch possibly, that would be useful in me building a linear cavity?




Amazing how far prices have dropped these days for many of the components for higher power Lasers, especially now how China is getting in on High tech manufacturing.

Q-switch would definitely still be useful. Can't comment on the mirrors because I don't know the specs on them. Depends on what sort of cavity you want too. There's a couple of folk on here with experience in building/repairing high power YAG lasers, they'd be able to offer some tips.

FYI, your diagram has a small error.

Red: 1064nm
Orange: 1064nm+532nm
Green: 532nm

It's not a whole lot cheaper, at least not if you're buying new parts. You'd still be looking at >$1000 to build a 3W 532nm unit from scratch using new parts. Probably >$2000. You can bring the price down considerably by buying used/surplus parts from places like eBay if you have some patience.

It's cheaper just to buy a unit from a supplier in China until you start getting into higher powers or you need really good specs, SLM, small beam diameter, good divergence, low M2, that sort of thing.