100W Laser repair!

TCWilliamson · Jul 28, 2016

Hello everyone.

I come to you today with my first laser (beyond those 5mW toy lasers)
I figured if I will go anywhere, I might as well go big so I purchases a second hand greenlight medical laser system. It employs a 100W (110W?) flash pumped laser.

The unit I purchased had it's screen smashed, leaving me to suspect the rest of it could well be ok! :thinking:

Before you start worrying or having concerns about a 'newbie' with such a laser. I have read quite a lot of the safety pointers here and I have 2 pairs of greenlight glasses that game with the unit for eye protection (though I'd still treat the laser as if I didn't have them in terms of safety)

I have yet to fix the cooling system up however I ran the unit on startup and it seems to fault out on the self-test for the flash lamp....

Having opened up the unit, I have attached pictures of the lot, including the flash bulb. (Don't worry. I have not touched it, just held it by the plastic holder. To me the tube looks fine? al-bit the connectors on each end are a little corroded....

It does have a Q-Switch and some very fancy looking water cooled optics under the black cover (that I probibly shouldn't have removed?)

Judging by the electronics. I have a feeling I will need to work out exactly how this whole thing works and redesign the control board as there is a lot of complex functions on it that I can't / won't use. (broken display unit etc.)

I'm rather excited to get this I hope I can fix it but all is not lost if I can't (it was 'only' £260) I wonder if I could Diode pump it if all goes wrong with the flash pumping circuit.

I'm hoping to build a laser cutter of sorts... or something else. What would you guys recommend?

diachi · Jul 28, 2016

TCWilliamson said:
Hello everyone.

I come to you today with my first laser (beyond those 5mW toy lasers)
I figured if I will go anywhere, I might as well go big so I purchases a second hand greenlight medical laser system. It employs a 100W (110W?) flash pumped laser.

The unit I purchased had it's screen smashed, leaving me to suspect the rest of it could well be ok! :thinking:

Before you start worrying or having concerns about a 'newbie' with such a laser. I have read quite a lot of the safety pointers here and I have 2 pairs of greenlight glasses that game with the unit for eye protection (though I'd still treat the laser as if I didn't have them in terms of safety)

I have yet to fix the cooling system up however I ran the unit on startup and it seems to fault out on the self-test for the flash lamp....

Having opened up the unit, I have attached pictures of the lot, including the flash bulb. (Don't worry. I have not touched it, just held it by the plastic holder. To me the tube looks fine? al-bit the connectors on each end are a little corroded....

It does have a Q-Switch and some very fancy looking water cooled optics under the black cover (that I probibly shouldn't have removed?)

Judging by the electronics. I have a feeling I will need to work out exactly how this whole thing works and redesign the control board as there is a lot of complex functions on it that I can't / won't use. (broken display unit etc.)

I'm rather excited to get this I hope I can fix it but all is not lost if I can't (it was 'only' £260) I wonder if I could Diode pump it if all goes wrong with the flash pumping circuit.

I'm hoping to build a laser cutter of sorts... or something else. What would you guys recommend?

A Q-switched arc-lamp pumped YAG for your first laser :wtf: ... This is a terrible idea all round. I've been messing around with lasers for 8 years and these things still scare the shit out of me - and I've been around several working models doing 40W@532nm, Q-switched. I know several people with more experience than me that refuse to go near something like this. Not just dangerous from the ridiculous output power (Major fire hazard, burn hazard, eye hazard, hazard to the space time continuum ... OK, that last one's a joke), but there's plenty of electrical components in there that'll quite happily kill you.

Which safety pointers have you read? I don't think there's really anything on this forum that adequately covers the safety measures needed for one of these.

There are a couple of people here (But more so on Photonlexicon) that know how to get these running. - including one guy who pretty much developed his own very similar system intended for show use. They may however refuse to help you due to previous issues with inexperienced operators running such systems. Much of the knowledge isn't public, and for good reason.

Modifying it to a diode pumped system is going to be far from trivial.

Edit: I know 2 or 3 people in the UK that can work on these systems - they are all active over on Photonlexicon.

TCWilliamson · Jul 28, 2016

Thank you for your reply!

I understand where you are coming from, currently I have it in the company workshop holed up to a side.
I've read a good few horror stories on the forum. I understand about how dangerous even dropping something vaguely reflective in the beam (as bad as anodized aluminum heatsink) could blind half the room) with such a powerful laser.
Thinking on that... I suppose with this power anything could be reflective, would the light reflected off smoke / water vapor be dangerous as well?

I have my glasses, I will look into getting a beam dump. (possibly a cylinder filled with pressed powdered carbon?)
Maybe you could pass me some more danger stories and 'just how much dangerous' it is compared to say, a 10W laser?

I think it would be safer for me to have guidance then to not have any. Hence why I'm here! I'm going to check out Photonlexicon in a moment, thanks for the advice there.

I'm fairly understanding of safety precautions in general, my other main 'hobby' is high voltage, I have a 70kV x-ray transformer plus a few others including a potential transformer.
I'm a collector of 'cool things' Well, I have a few projects I'm gradually saving up components for (Ion mill, fusor, SLS printer, laser cutter)

I'd rather not be foolish. I want to learn.

.... and to think I was originally going to buy this one.

diachi · Jul 28, 2016

TCWilliamson said:
Thank you for your reply!

I understand where you are coming from, currently I have it in the company workshop holed up to a side.
I've read a good few horror stories on the forum. I understand about how dangerous even dropping something vaguely reflective in the beam (as bad as anodized aluminum heatsink) could blind half the room) with such a powerful laser.
Thinking on that... I suppose with this power anything could be reflective, would the light reflected off smoke / water vapor be dangerous as well?

I have my glasses, I will look into getting a beam dump. (possibly a cylinder filled with pressed powdered carbon?)
Maybe you could pass me some more danger stories and 'just how much dangerous' it is compared to say, a 10W laser?

I think it would be safer for me to have guidance then to not have any. Hence why I'm here! I'm going to check out Photonlexicon in a moment, thanks for the advice there.

I'm fairly understanding of safety precautions in general, my other main 'hobby' is high voltage, I have a 70kV x-ray transformer plus a few others including a potential transformer.
I'm a collector of 'cool things' Well, I have a few projects I'm gradually saving up components for (Ion mill, fusor, SLS printer, laser cutter)

I'm not ignorant. I want to learn.

A diffuse reflection from a white wall at ~20m could potentially cause eye damage IIRC. That's how dangerous these are. Keep in mind the 100W rating is average power. Peak power is into the 10s of kWs on something like this. There's enough power coming out of these to ionize air at regular atmospheric pressures.

Actually getting one of these up to a useful state is not easy. Especially if it's in an unknown/damaged condition.

As for beam stops (Apparently I can't type d*u*m*p*s...

Just get *****... ) -commercial ones seem to be either graphite or aluminum - water cooled for the higher power stops.

PL is definitely the best place to ask. If someone is near you they may be able to meet up with you to look over the system. Stanwax or Daniel Briggs over there are probably your best bets.

Ahh good - at least you have some experience with high voltage and such, that's reassuring.

:beer:

Edit: feel free to post some of your non-laser related projects in the "other" section - I'm sure many of us would be interested in those too! :beer:

TCWilliamson · Jul 28, 2016

diachi said:
A diffuse reflection from a white wall at ~20m could potentially cause eye damage IIRC. That's how dangerous these are. Keep in mind the 100W rating is average power. Peak power is into the 10s of kWs on something like this. There's enough power coming out of these to ionize air at regular atmospheric pressures.

Well fuck... it's a good thing it failed to power up properly earlier on.:wtf:
I'm going to be shaking every time I run a test with it now... probibly for the better!

diachi said:
Actually getting one of these up to a useful state is not easy. Especially if it's in an unknown/damaged condition.

If I wanted an easy project I would have become a woodknocker!

diachi said:
As for beam ***** -commercial ones seem to be either graphite or aluminum - water cooled for the higher power *****.

Cool, I can knock this up with a small graphite crucible I have and a quick machine job for an aluminium waterblock once I have my lathe sorted out.

diachi said:
PL is definitely the best place to ask. If someone is near you they may be able to meet up with you to look over the system. Stanwax or Daniel Briggs over there are probably your best bets.

I'll post this all over now.

diachi said:
Ahh good - at least you have some experience with high voltage and such, that's reassuring. :beer:

Indeed!

For some background to establish some 'trust' on such information.

I'm 19Yrs, I work for a company as an Electronic / Applications Engineer and do a fair bit of electronics / CAD work there including motor design, drive design, demo design, microcontroller programming etc.

I have good experience with power electronics (500J+ capacitors, 70kV transformers, heavy duty switching power stages)

I'm currently doing an HNC in EE.

diachi · Jul 28, 2016

TCWilliamson said:
Well fuck... it's a good thing it failed to power up properly earlier on.:wtf:
I'm going to be shaking every time I run a test with it now... probibly for the better!

Good to have the fear around these I'd say - means you're constantly aware of the dangers.

If I wanted an easy project I would have become a woodknocker!

Can't argue with that!

Cool, I can knock this up with a small graphite crucible I have and a quick machine job for an aluminium waterblock once I have my lathe sorted out.

That should work - chunk of concrete would probably do the job just fine, just doesn't absorb as much light. The aluminium stops are black anodized IIRC.

I'll post this all over now.

Indeed!

For some background to establish some 'trust' on such information.

I'm 19Yrs, I work for a company as an Electronic / Applications Engineer and do a fair bit of electronics / CAD work there including motor design, drive design, demo design, microcontroller programming etc.

I have good experience with power electronics (500J+ capacitors, 70kV transformers, heavy duty switching power stages)

I'm currently doing an HNC in EE.

Got a young one eh?

Saying that as if I'm much older ... I'm not. HNC? Are you from Scotland ... or are there HNC courses in other parts of the UK too (I'm from Scotland, moved to Canada 3.5 years ago)? Nothing that high voltage in these - but the lamps run a few hundred volts DC at a good 30-40A IIRC.

Water in these needs to be good DI water - it comes in direct contact with the lamp electrodes - having not-DI-enough water will cause some big issues. There's enough power involved that not following the correct mirror alignment procedure on the cavity mirrors will cause the beam to literally blast away the surface of the mirrors. Of course, cavity power is going to be a good bit higher than output power...

Search over on PL for "laserscope 800" - lots of threads there talking about dangers and various other things for these types of systems. Although not really how to get one running. IIRC PL search is terrible - may want to use google to search PL. :beer: This should get you started: https://www.google.ca/?ion=1&espv=2#q=laserscope 800 site:photonlexicon.com - Can't remember how similar those are to the greenlight systems, but should be somewhat similar. Skills are transferable - I know a few folk over on PL have had greenlight systems too. Maybe search on PL for greenlight too...

If you're in Scotland try reaching out to gashead over on PL - he's a Kiwi living in Scotland, although he may be overseas at the moment. He has experience with these sorts of systems too.

TCWilliamson · Jul 28, 2016

diachi said:
Got a young one eh Saying that as if I'm much older ... I'm not? HNC? Are you from Scotland ... or are there HNC courses in other parts of the UK too? Nothing that high voltage in these - but the lamps run a few hundred volts DC at a good 30-40A IIRC.

Search over on PL for "laserscope 800" - lots of threads there talking about dangers and various other things for these types of systems. Although not really how to get one running. IIRC PL search is terrible - may want to use google to search PL. :beer:

If you're in Scotland try reaching out to gashead over on PL - he's a Kiwi living in Scotland, although he may be overseas at the moment. He has experience with these sorts of systems too.

Yes, this one is 230V @ 40A, has a beautiful 1:1 isolation transformer in it.. Buying the unit for that alone was worth it to add to my 40A Variac stack.

Where am I? Other end I'm afraid! I'm in Dorset (South) area!

We do have HNCs down here, it's a work based path towards degree.

https://www.photonlexicon.com/forum...operational-functionality?p=329522#post329522

diachi · Jul 28, 2016

TCWilliamson said:
Yes, this one is 230V @ 40A, has a beautiful 1:1 isolation transformer in it.. Buying the unit for that alone was worth it to add to my 40A Variac stack.

Where am I? Other end I'm afraid! I'm in Dorset (South) area!

We do have HNCs down here, it's a work based path towards degree.

Where would you recommend I post in PL? I feel that the modifications forum would be best?

Oh yeah ... I remember having to move one of those transformers, they weigh a bloody ton. Glad the one we were using was in a case with handles. Last system I was around was broken up into 3 or 4 parts in separate flight cases, made moving it around much easier. Those LS 800s weigh something like 300lbs.

Ahh - yeah - works the same way in Scotland, for some reason I thought HNCs were only in Scotland - I know the secondary school system is different, maybe that's why I'm getting confused.

Either: "Lasers, All Kinds" or "Modifications" as you suggested would probably be the best place.

TCWilliamson · Jul 28, 2016

diachi said:
Oh yeah ... I remember having to move one of those transformers, they weigh a bloody ton. Glad the one we were using was in a case with handles. Last system I was around was broken up into 3 or 4 parts in separate flight cases, made moving it around much easier. Those LS 800s weigh something like 300lbs.

In my mind from the HV hobbiest forums, It's not real fun until you need a forklift!

diachi · Jul 28, 2016

TCWilliamson said:
In my mind from the HV hobbiest forums, It's not real fun until you need a forklift!

Oh yeah ... I can't argue with that haha

. Perhaps if I didn't live in an apartment I'd get into HV stuff. Saying that, I'd probably cause a city wide power outage. We've already had two in the last two hours. Last one was half an hour ... this one will hopefully be shorter. So much for making lunch!

Photonicinduction has to be one of my favourite YouTube channels - not far from needing a forklift for some of his kit.

TCWilliamson · Jul 28, 2016

diachi said:
Oh yeah ... I can't argue with that haha . Perhaps if I didn't live in an apartment I'd get into HV stuff. Saying that, I'd probably cause a city wide power outage. We've already had two in the last two hours. Last one was half an hour ... this one will hopefully be shorter. So much for making lunch!

Photonicinduction has to be one of my favourite YouTube channels - not far from needing a forklift for some of his kit.

Indeed! I can easily fit an entire houses power supply though my 70kV transformer if I was man enough to raise the input voltage. It's rated for 25kW! (momentry) It looks crazy enough on 80V input, let alone the 450V input!

DashApple · Jul 28, 2016

Good luck : D ,

I had a 100W Lamp pumped 1064nm CW , Had a lamp failure so the system was parted out and sold as bits , I still have the trigger transformer and arc lamp power supply from it along with the 45A rated mains filter and a very large stainless steal and copper finned radiator

Did get it running at 80W for a short duration

TCWilliamson · Jul 28, 2016

DashApple said:
Good luck : D ,

I had a 100W Lamp pumped 1064nm CW , Had a lamp failure so the system was parted out and sold as bits , I still have the trigger transformer and arc lamp power supply from it along with the 45A rated mains filter and a very large stainless steal and copper finned radiator

Did get it running at 80W for a short duration

Ah cool, interesting!

I'm beginning to feel my laser is old tech, I'm looking on youtube and seeing these 80W lasers the size of my wallet with a power supply the size of a keyboard... compared to my filing cabinet!

diachi · Jul 28, 2016

TCWilliamson said:
Ah cool, interesting!

I'm beginning to feel my laser is old tech, I'm looking on youtube and seeing these 80W lasers the size of my wallet with a power supply the size of a keyboard... compared to my filing cabinet!

Yeah... Diode pumped instead of lamp pumped did make a huge difference when it came to size and efficiency.

TCWilliamson · Jul 28, 2016

diachi said:
Yeah... Diode pumped instead of lamp pumped did make a huge difference when it came to size and efficiency.

Indeed

I wonder how many diodes I can pump into that rod...

and for that matter, how can I tell what type of doping the YAG rod has.. and how much does it matter to me? (a lot I'm betting from what I have read...)

diachi · Jul 28, 2016

TCWilliamson said:
Indeed

I wonder how many diodes I can pump into that rod...

and for that matter, how can I tell what type of doping the YAG rod has.. and how much does it matter to me? (a lot I'm betting from what I have read...)

Could probably dump at least a good 200-300W optical power into that rod I'd say.

That's not the issue ... the rod/lamp cavity would need to be substantially modified/completely replaced in order to support diode pumping. The configuration is different and you still need water cooling for both the rod and the diodes at those kind of powers. You'd need to transverse pump it (more commonly called side pump) to achieve any reasonable amount of performance.

Assuming this is the same laser I think it is then it's Nd doped. Any laser warning stickers on there? They'll tell you laser type and emitted wavelengths. Not sure on Nd percentage, I'd only be guessing if I gave you a number. Going to take a guess and say ~0.8% or around there but I may be entirely wrong there.

For continuous wave output, the doping is significantly lower than for pulsed lasers. The lightly doped CW rods can be optically distinguished by being less colored, almost white, while higher-doped rods are pink-purplish.

100W Laser repair!

TCWilliamson

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