Dpss yag laser

Last August, there was a large laser head listed on ebay as 'Coherent Laser Head'. Originally the seller wanted something like $3000 for it, and over the next few weeks he worked his way down, until I finally got for it for $1000. Then I ran into trouble, Ben was drooling over the head and wanted to see what was inside and post the pictures on his photostream, so he said hey let me go pick it up and since I know how to ship lasers I will ship it to you, that way you will know it will get packaged well and won't get damaged in shipping. So I said sure, and pictures were taken, the head was identified as a Avia Thor (15w 355nm) and the laser was shipped to me. Unfortunately, as it turns out Ben does not in fact know how to ship big lasers, and when the ups man set it on my porch I could hear pieces rattling. The first sign of trouble was this corner:
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Then I started taking out screws, and got to see what was inside, and it was pretty ugly...


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The root cause ended up being the box was dropped on its corner, from high enough that the foam just didn't cut it, which put the dent in the lid and snapped off the front mount for the plate with all of the optics. The, along the rest of the journey the plate was just flapping around inside, snapping optics off left and right. Luckily, Ben knows how to cover his ass, and shipped the head insured, and after a 6 month long battle with UPS I managed to get a refund for the head :)

But, I was still left with one problem, I now have a pair donut modules a pair of crystals (one for SHG and one for THG) and a few assorted optics that didn't get destroyed (some 45 degree turning mirrors, a waveplate, nothing too fun)

So I started doing some head scratching, and spent a few late nights playing with solidworks, until I had reverse engineered the donuts and devised a way to properly mount them on my breadboard and get power/water plumbed into them.

The disassembly of the donut modules:
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Then I did some drawing:
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Followed by some machining, plumbing and wiring:
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And some lasing!

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Any new guess on power output?

looking at these 3 donut pumps, I'd say 200-ish watts of YAG power... but I doubt ^^

Do you mean output power or pump power?

I am running the pumps about 250w right now (I do not know what they were rated for, but I am assuming they are 20w diodes, which gives 300w total)

Wow, what output do you get?
What are you going to use it for?
Looks proper hightech! :)

Wow! Sexy, exciting view !
As I'm about to do similiar thing but with 5 donuts, I'd love to ask You what rod dia did You choose ? Any FAC optics for diodes ? Do You have separate water flow for YAG and donuts ?
Piotr.K

That is one of two modules out of a Coherent AVIA THOR 15W 355nm System.

Hmmm, You mean it's a factory built module ... then sexiness factor must be square-rooted :)
In my 'design' I'm at the stage of practising DIY lathe work for donut start-end modules :cool:
I'm planning to route YAG & bars water flow separately :confused:
Piotr.K

6 posts and only one guess on the power? Come on guys :rolleyes:

But since the project is already starting to get attacked by those who are jelous, I will start sharing *retaro

See the first post for updates

And the moral is: No matter how much he might beg, DO NOT let Ben have temporary custody of your lasers unless you're right there with him and can take it home with you.

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Originally Posted by krazer

Then I ran into trouble, Ben was drooling over the head and wanted to see what was inside and post the pictures on his photostream, so he said hey let me go pick it up and since I know how to ship lasers I will ship it to you, that way you will know it will get packaged well and won't get damaged in shipping.

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Well, where to start...

First off, you asked me to pick it up and ship it, I did not ask you to let me do that.

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Peter: I was thinking of having you pick i up
you are not that far away from what i understand
me: yeah

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Secondly, you told me it was fine to open it and document it all I wanted.

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Peter: but yeah document it all you want

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Finally, it was packed with 6" of medium density foam on all sided. That is more foam then Coherent uses when they ship the system! I had no way to know that UPS would drop do so much damage to the box that it would dent and crush a 3/32" thick aluminum cover. The laser was reboxed

When it was discovered that it was damaged, we worked together on the UPS claim (which paid out the full amount of the laser, and shipping). You got every part of the laser that survived, which was most of the pump module, the crystals, heaters, and many of the optics.

Considering that it was packed better then Coherent, I was amazed that UPS destroyed the laser. You ended up with a free pair of pump units, 2 LBO crystals and heaters, an XYZ stage, and a whole bunch of other parts.

hrmm, maybe by blue got dropped too? and all my mW's fell out of the box? ;)

(sorry had to)

thats some serious power in a tiny package!!!

Well, pumping with 300W of 808nm would give say 65W of 1064nm, multimode, CW.
But I'm not sure if You're controlling temp in the water circuit ...:confused:
Piotr.K

Dude!
That head is SWEET! I want one! *retardo

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Originally Posted by LesioQ

Well, pumping with 300W of 808nm would give say 65W of 1064nm, multimode, CW.
But I'm not sure if You're controlling temp in the water circuit ...:confused:
Piotr.K

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Now were getting close!

Running CW I am getting just over 40w, and as I noted earlier I haven't been able to measure the beam profile yet, but if I did my guessing right I should be running single mode. The resonator consists of a 0.75m HR and a plano OC that is 80% reflection, that are 18" apart.

Now for some fun stuff, I added in a small q-switch. Sadly it is undersized for this laser, and with the 80% OC it can only blank the output down to about 10w, but still adds a fair bit of umph *retardo

Here is a poor razor blade that I decided to try it out on:
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First is a shot of the cutting process (sorry about the rigjob on the focusing lens, the only lens I had handy had a stupid diameter so I couldn't find a mount for it), a shot of after the center piece fell out, and a macro shot of the cut edge.

Go to a UPS facility, see the 3-4 foot drop into the sorting bin. See packages fall off unfenced convayors.. See your stuff land on other people's stuff! See other peoples stuff land on your stuff.

Find that since they are self insured, nothing less then a lawyer and the Warsaw convention get you paid...

Cost me at least 1500$ over the past 15 years. Including 700$ in one swoop.

I go to the post office or FEDEX for a reason, big stuff goes truck freight in a wooden outer case, with the inners on preloaded springs, or double foamed boxes...

Nice build Krazer, your the first one I've seen in a long time get donuts to lase something, will we be seeing a V fold in the near future, or a external doubler?

Steve

Ok I know its my failt for mentioning the B word in the thread, but please keep your gripes in the correct thread.

Sadly you probably won't be seeing much more till summer comes, I am headed back to school and the beast isn't coming with me. The long term plans for it is to get a beefier q-switch, add in the second pump module, and tweak the cavity a bit to try and extract a bit more power, my goal is to hit 100w q-switched with the pair of pumps. The doubler LBO out of the head survived, so I am planning to have a way to add that in for doubling extracavity for cutting materials that do not absorb 1064nm.

I designed the plate that the pumps attach to to be 'easily' removable (although I forgot about the electrical connections when I was planning that out) so that it could be swapped between heads to try something like a V-fold, but that is still probably a few years off. Plus what would I do with 50w CW green anyway *retardo


To answer a few trailing questions:
I am using a Lytron RC009 chiller, I measured max power with the head at 30c, which when running at 25A needs the water at 23c (which means that the effective thermal conductivity of each donut is .035C/W with about 2 gpm of flow, in case anyone is interested)

The rod is a 3mm rod, and the need for FAC was solved by a funky flow tube design The flow tube is very thick, and has a HR@808nm coating on it, with 5 slots in it, which are aligned with the diodes, so that the beam can enter through the slots, go through the rod, then reflect back for a second pass (or at least that is how I think it works). There also have to be some effects due to the thickness that I would need to do some ray tracing to understand.

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It is hard to see how the flow works from the pictures, but you can download the solidworks model from my website, where it can be seen the flow for the rod and diodes is indeed separate. There are 2 holes on each of the end caps, one of them goes through the diffusers shown in the first post and then over the rod, the other one goes through the cooling channels in the diodes. I currently have it looped so that it goes through diodes then back out through the rod (that is how it was plumbed in the Avia head I got them out of), and it seems to work fine. I haven't measured the difference in the water temperature, but a rough calculation says there should be about 1c change between the inllet to outlet temperature of each bar. Coincidently, with 3 bars in series and the 23c water I am using that would put the rod exactly at 25c, so maybe someone at coherent was being smart when the picked the diodes wavelengths.


Anything in particular you guys would like to see it unleashed on before I head back to school? I want to let it drill a hole through a nice chunk of aluminum just to see how deep I can go and keep a clean edge, but I am open to suggestions *retardohttp://www.photonlexicon.com/forums/...isc/pencil.png

Fantastic! I vote for a piece of alu too, try 1cm maybe with air assist to get rid of debris.

maybe an angled hole? like 15 degrees, it would really tell about the beam quality and power if the edges are, well, like cutting

you could even try to make a carrot reaper *retardo

Well sadly I don't have time to build a gas assist for it, so for now this is done be just holding the part in front of the laser. I also ran into trouble with the aluminum, it reflects pretty well and I couldn't get good coupling, which in combination with the lack of any gas assist make cutting pretty dismal. So I switched back to steel, and took a few more pictures.
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The fist one is shooting strait into the plate, the second one was taken at a pretty steep angle (15 degrees guessing). In both shots the cut is 250um in diameter, and its hard to see in these pictures since its really hard to focus in a hole (har har har), but the edge is suprisingly clean, probably flat to about 10um.

really great! makes a nice cutting tool :)

Anything in particular you guys would like to see it unleashed on before I head back to school? I want to let it drill a hole through a nice chunk of aluminum just to see how deep I can go and keep a clean edge, but I am open to suggestions *retardohttp://www.photonlexicon.com/forums/...isc/pencil.png[/QUOTE]

GLASS please...

Steve

Raising the dead here, been a very long time since this thread has been active.... but, might anyone know what the CW output of one ND:YAG is and what can be had with two, as originally configured?

... my two old ones had 120W and 150W (salvaged and sold) ... actually have a "medical" with 60W ... but not "CW" but "averaged" :cool:

You could get 120+ watts out of one single ND:YAG from the Avia Thor when pumped at 300 watts? Impressive, especially 150W. Just wanted to confirm this is possible from a three diode ring Avia Thor ND:YAG, thanks.

... the two old ones (120W/150W) were not DPSS, but flas-lamp pumped ... much lower efficiency, as with diodes -- I'll estimate something like 3-5%, instead of around 35% with DPSS.

I've stored one of the resonator chambers and got some water-cooled 405nm-LED's with 9W and 100W output, to pump ruby-rods -- I have two rods, but "old style", not doped for DPSS but flash-lamps ...

Ah, 120+ with flash lamp. Best I've come to find for the ND:YAG output of the diode pump driven 300W Avia Thor head is about 40 watts for a single head, but when searching online for typical output percentage of the pumped power for 1064 nm output, estimates are much higher. Appears I have a bad resource or didn't ask the question properly on x.ai - I know, ai gives bad answers frequently, depends upon their source and ai "thinking" process.

... for typical power-efficiency with diode pumped lasers, here some numbers:

Sometimes around 2005 I had a "disk"-laser with 20Watts averaged, which was pumped with a 60Watt IR-laserdiode-module.

Modern fiberlasers too needs around 3x the later "averaged" output power as combined IR-pump-laserdiodes -- output efficency specified as 35% ... so not much efficiency development in 20 years :rolleyes:

The donut diode rings are each 100 watts, I believe this is likely DC watts into the diodes, three 100 watt rings producing 300 watts at 50% efficiency would be 150 watts of IR pump power, so it stands to reason the output of the ND:YAG is 1/3, or 50 watts, perhaps 60. Is my reasoning valid?

... sounds reasonable :cool:

On the other side - when only shortly activated (and with massive cooling), diodes can be "overpowered" with up to 50% for some millisconds and up to several 100% for microseconds ... then they'll need some seconds for cooling down.

So for "pulsing" applications this could be much more >:)

Pulsed high current DC to the diodes, I don't have a power supply capable of doing so but for now, want to use them at a constant current with a AOM or something to produce short bursts, high peak power out of the ND:YAG to produce more efficient SHG conversion to green.

I was wrong about the IR power of these donuts, 100 watts output is what they are rated to produce, so I'm hopeful to get at least 75W CW out of a three donut head. Anyone believe this expectation to be high?

... with 100Watts pump power in a DPSS setup with AOM modulation the estimated pulse-peak-power should be something like some 10 to 100 Kilowatts and the averaged "CW" power is highly depending on the cooling methodes :cool:

There are three 100W ring diode pumps in one ND:YAG head for this one, so that's 300 watts of IR pump into one YAG.

... so in optimal setup around 100Watts averaged.

If I think about te actual DPSS IR-Laserdiode modules wit 2Watts "output power" (read "averaged") -- they're pumping with a 25W-IR-Laserdiode and AFAIK 808nm wavelength ...

Each ring has five diode assemblies, each producing 20 watts IR.

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... interesting design -- round 20 years ago I've helped to assemble the "ringfocus-laser", where 80(!) 20W-Diodes were collimated and the beams combined into 1.6kW on a "spot" roughly 6mm wide for metal welding.

Actually I have many IR-Laserdiodes with up to 40W fed through 0,1mm-fibers or bigger modules with up to 360W, focus combined into a spot of 0,2mm -- much more energy density :cool:

But it's mostly with 975nm, as for fiber-lasers, not 810nm, like for Nd:YAG's ...

I have a lot of laser junk, mostly good parts, but no lasers which produce more than 10W at 532 nm. Would like to use these heads, have three of them, to build a high power 532 nm laser using one or two if OSC and PA arrangement.

... ah, so meant for frequency doubling -- then good luck!

What else to do with 1064 nm :p

It's a long term project, but I have a few of them...... I made a SHG once before using 1064 nm out of a 15 KW peak power pulsed YAG, average power was only a few watts at 1064.

... when powerfull enough, then it's pretty good suited for metal: - welding, melting, cutting ... and "3D-printing" >:)

The 40W@975nm-diodes with attached 0,1mm-fibers were already enough, to melt lowtemp melting metal powder or many (dark) powders of other materials like plastic, lignin, glass and ceramic ... several of them with combined fiber tips could be focussed on a spot with roughly 0,2 to 0,3mm ... have some of this type with 40W, 30W and 25W (and "many" with 9W) -- could be easily combined to 1kW or more.

Of the bigger modules I too have some tens of different types (but same build) with output powers of 360W, 310W, 260W, 200W and 135W ... when combined, enough to form a spot of roughly 0,5mm and up do some ten Kilowatts! -- with this types I'm developing some sort of "metal wire FDM-printing" :cool:


*** EDIT *** - attached are some images of the smaller diodes with attached fiber and some of the bigger modules:

I have a lot of 35W 975 nm fiber modules which were sold as tested and good, the ones I powered up were, but I don't use lasers for anything practical, just for fun and still have two eyes too. I live out in a very rural area and have room to play, no airports anywhere near me but also not pointing into the sky here either. Although, would love to shoot a high power 532 nm strait up into the night sky someday though.

Edit: I was purely joking about what else to use 1064 nm for :p

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Originally Posted by Laser57

I have a lot of 35W 975 nm fiber modules which were sold as tested and good, the ones I powered up were, but I don't use lasers for anything practical, just for fun and still have two eyes too. I live out in a very rural area and have room to play, no airports anywhere near me but also not pointing into the sky here either. Although, would love to shoot a high power 532 nm strait up into the night sky someday though.

Edit: I was purely joking about what else to use 1064 nm for :p

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my personal favorite is trippling + OPO, that way you get adjustable rainbow.