PGL-III-C 671nm 100mW+ re-alignment

[ultimatekaiser]

I got a PGL-C from Wannaburnstuff a while back, and it has always been a good laser, but massively multimode and horribly unstable, so I recently had to fix my aries and his own 800mW 532, I decided to peek in this one while I had my stuff out.

inside after removing the lens:

module out:

It so happens to have turned out that it was actually not even originally aligned properly!

As you can fairly well see in the pic, there were several bright obvious sets of internal reflections that were stray inside the laser head, (though some are hidden in the glare in the pic a total of 5 easy to see spots) and it was massively over current fed to get the power. this resulted in tons of power for a few seconds when turned on, then rapid over-heat, and tons of mode hopping for a long time till it reached a very hot thermal equilibrium. I dropped the current a bit, and realigned the module to where it seems much more comfortable. It's now a bit weaker, but it outputs a strong and steady TEM00, and as a result, battery life and heat has been improved, despite overall power loss. perhaps I should put this bad boy in a custom host!

After fix:

natural beamshot after fix at 300mW+ Tripled the power!

 

[NKO29]

Re: PGL-III-C 671 repair

Nice to see that you fixed it How long did the repair take?

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

after I got the module out, not long. about 20 minutes ish. I may fiddle more to get max power out of it sometime, but for now i'm leaving it as is.

 

[jeffreythe00]

Re: PGL-III-C 671 repair

Great info!

I don't understand why some of these CNI lasers are so horribly put together! Are they really in such a hurry to build these lasers that they can't take at "least" a few extra minutes to stabilize the lasers they are sending out? You'd think directly from CNI, these lasers would be super fine tuned. Instead leave it to a hobbiest to correct the problems.

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

some of them are probably done initially by a machine i'm sure to save time. they probably just throw them together to get the power they need, and then out it goes because it still meets spec. I don't imagine that the handhelds they care much about. its the labbies that really matter. hence, you get what you pay for. plus, it just goes to show no company is perfect. I've actually seen alot of CNIs that are like this. my 473 pointer is like this too, but i'm not tempted to do anything to it. also, It gave more power slightly offcenter, because more total light passed through the medium as it was before, so despite the horrible beam quality, I think that may have something to do with it.

makes me curious if I could tweak and fine tune some of the other colors such as the yellows to be better...quite the intriguing thought.

 

[dubious speculation]

Re: PGL-III-C 671 repair

Nice tear-down thread :beer: I would be way to scared to mess around with the optics in that thing let alone have any hope of fixing it

I suppose that's one of the advantages of buying CNI pointers from laserglow. Because (I assume) that they test each pointer before they sell them. It looks like quite a few members have had issues with their CNI lasers. Wannaburnstuff's 532 PGL-III-C for example. He hasn't had it for that long and already it's got issues. You'd think that if you spent that much money on a laser CNI would at least make it their priority to quality test every laser before it's shipped.

 

[crazyspaz]

Re: PGL-III-C 671 repair

I always enjoy seeing the inside of CNI's modules. Such a convenient way to align everything- a while ago before i ever saw the innards of one, I had almost the same idea for a module, except with the individual blocks on auger type deals, adjustable via screw. Just to keep everything parallel. How much power is it outputting now vs. before?

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

Well they don't always come out perfectly parallel unless you're using the crystal surfaces as your mirrors. I also am not sure what it did before as it was never metered, and I don't have an LPM sadly. I'd need a good Ophir, and I just can't afford it. I'm basing the power drop on what seems to be a drop in power. I'm under the impression the avg power has increased, but the peak has substantially decreased judging from brightness, but as we all know, that's not a reliable way to tell.

 

[BShanahan14rulz]

Re: PGL-III-C 671 repair

My post count belies my actual knowledge, so keep that in mind, but to me it makes sense that now, in TEM00 mode, you have less overall power. Less volume of the gain medium is being pumped, and that single resonating mode is "maxed out," and without other "hotspots" in the medium also resonating and adding to the overall power, the observed output decreases.

Kind of like how it is hard to get single-mode diodes in high powers, because there is only so much power a small volume of material can take. Hence, higher power diodes have larger active regions.

So, what exactly is involved in aligning a setup like this? Is it just loosen the bits enough to allow adjustment, adjust until it looks good, tighten the mounts or glue 'em down, and verify adjustment is still good?

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

No you're absolutely right. I'm still planning on tweaking the module a bit, so I'll be sure to share. More is to come so keep an eye open. Achieving doubling isn't too hard, as long as everything is positioned and oriented correctly, stabilizing it however, takes many hours.

 

[crazyspaz]

Re: PGL-III-C 671 repair

Well they don't always come out perfectly parallel unless you're using the crystal surfaces as your mirrors. I also am not sure what it did before as it was never metered, and I don't have an LPM sadly. I'd need a good Ophir, and I just can't afford it. I'm basing the power drop on what seems to be a drop in power. I'm under the impression the avg power has increased, but the peak has substantially decreased judging from brightness, but as we all know, that's not a reliable way to tell.

So does CNI use AR/HR mirrors after the Nd:YVO4, Nd:YAG, or what have you, as well as the KTP (output coupler), rather than just having AR/HR surfaces on the crystal itself? Seems like it would be easier to get the beam parallel by just AR coating the output side of the crystal. But, I see how it would make over all alignment more difficult...

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

The lab modules use a different setup than the handhelds. That being said, I have not tested each piece individually, and each wavelength is a bit different. This one is:

808 pump -> coupling lens -> Nd:YVO4 -> LBO -> OC -> correction -> IR filter -> collimating lens -> aperture

Majority of the mirror coatings appear to be on the crystals, but not all of them

I'd love to work on and perfect a 589 module to see how all the different ones are laid out. I enjoy fixing these. It's a pain, but I love tinkering, especially when I know I can make it better than it was by far. Multimode lasers are no fun in my opinion, and I wager a lot of the crummy 589 stuff is just as fixable to someone like me with fine attention to detail and a steady hand and some time for those who desire quality.

 

[crazyspaz]

Re: PGL-III-C 671 repair

Theres no doubt in my mind you could get more output out of a 589 module-CNI is great and all, but I highly doubt they have the most skilled work force, if you will, for this particular field.

 

[ultimatekaiser]

Re: PGL-III-C 671 repair

I wouldn't say that... I'd say the know what they're doing, but I frequently see things that just scream "lazy" or "rushed" where they just throw it together and go "ok it's working for minimum 45 sec spec, send it out and move on to the next one"

 

[crazyspaz]

Re: PGL-III-C 671 repair

My thoughts exactly. But man would I love to spend a day inside of CNI with unlimited access.....

 

[IsaacT]

Re: PGL-III-C 671 repair

This is awesome, I was hoping I would get to see the fruits of your efforts on that laser. I cannot wait until Ehgemus receives my 532nm module so he can start on the host I requested

So I did some digging to find out, because I know I LPM'd it, just never reviewed it. I finally found a post I had made forever ago.

It started around 150mW and then dropped to 70mW after 20-30 seconds and then slowly down to 50mW over a long period of time. So you may end up seeing a net increase in power simply from decreasing the initial power. Hopefully you can find or obtain an LPM to test it. If not you can feel free to ship it to me and I will measure it for you.