CNI 589nm Rebuild Questions

[styropyro]

(Don't worry, this isn't my new yellow Spartan )

So a couple years ago I bought a broken 10mW CNI 589nm unit thinking that it's only issue was its switch. I ripped it apart and shorted the switch, and found that the laser produced no yellow light, even though the IR pump diode fired up nicely. I then put the module away for some time and didn't start messing with it until a couple months ago.

I started by adjusting the crystal mounts with no luck. I tried rotating the crystals, as well as repositioning the OC, and even replacing the diode without any luck. The best I can get is a small spec of light visible on the first crystal, as seen in this pic (along with IR)

So my first question is, why on earth am I seeing yellow light on the first crystal?? I thought the process was LD > Nd:YAG > KTP, so I shouldn't be seeing visible light from the first crystal.

And my more general question is, does anybody have any extra tips for alligning a 589nm unit? I've repaired many of the BW 473nm units, but this seems to be a different game.

Thanks in advance for any help!

 

[diachi]

(Don't worry, this isn't my new yellow Spartan )

So a couple years ago I bought a broken 10mW CNI 589nm unit thinking that it's only issue was its switch. I ripped it apart and shorted the switch, and found that the laser produced no yellow light, even though the IR pump diode fired up nicely. I then put the module away for some time and didn't start messing with it until a couple months ago.

I started by adjusting the crystal mounts with no luck. I tried rotating the crystals, as well as repositioning the OC, and even replacing the diode without any luck. The best I can get is a small spec of light visible on the first crystal, as seen in this pic (along with IR)

So my first question is, why on earth am I seeing yellow light on the first crystal?? I thought the process was LD > Nd:YAG > KTP, so I shouldn't be seeing visible light from the first crystal.

And my more general question is, does anybody have any extra tips for alligning a 589nm unit? I've repaired many of the BW 473nm units, but this seems to be a different game.

Thanks in advance for any help!

Are you sure that is Nd:YAG and not Nd:YVO4? I've noticed that fluoresces visibly a little while being pumped.

Check for cracks in the YAG/YVO4, that could stop it lasing, a magnifying glass and some bright light may help you there, and keep in mind that YVO4 is sensitive to the polarization of your pump diode too.

 

[Sigurthr]

My bet is cracked vanadate, let's hope it is just alignment though. You can be off by a tiny amount and see no lasing since this is SFG and not SHG.

 

[diachi]

My bet is cracked vanadate, let's hope it is just alignment though. You can be off by a tiny amount and see no lasing since this is SFG and not SHG.

I'd put my money on cracked vanadate too. But also, hope that it is just alignment.

Depending on how much it's worth to you, you could replace the vanadate, but a one off piece with the correct coatings won't be cheap.

 

[Davidx]

Love this forum. Where else could you ask what to a normal person is a very technical questions, and get so many intelligent answers from our other clever members?
I admire your cohones for just taking it apart. LOL

 

[Pman]

I certainly can't help but honestly wish you all the best trying to fix it. I can tell it would give you great satisfaction.

 

[styropyro]

Are you sure that is Nd:YAG and not Nd:YVO4?

No, I am actually not sure. I'll have to do some reading to be able to tell the difference.

My bet is cracked vanadate, let's hope it is just alignment though. You can be off by a tiny amount and see no lasing since this is SFG and not SHG.

I took some light and shone it trough the crystal and sure enough, there is at least a defect in it that is likely a crack. I guess I'll stop wasting my time with the alignment!

Thanks for the help guys, would rep you both if I could!!

 

[diachi]

No, I am actually not sure. I'll have to do some reading to be able to tell the difference.



I took some light and shone it trough the crystal and sure enough, there is at least a defect in it that is likely a crack. I guess I'll stop wasting my time with the alignment!

Thanks for the help guys, would rep you both if I could!!

Glad I could help! That's unfortunate that the crystal is damaged though :cryyy:. You could buy a piece of vanadate to replace it but it would probably be cheaper just to buy whole new laser.

 

[crazyspaz]

Darn it's broken, guess you should give it to me (jk)
I would drop kaiser a pm, he's a wazard when it comes to solid state. And he would probably be your best bet for getting a replacement crystal. Also, I have a 3.5W 808 c mount that I doubt I will ever get to use if you find yourself needing one, although I think those PGL-C modules used 4 or 5W pumps if im not mistaken.

 

[Sigurthr]

Is yours integral mirror or external mirror? Makes a huge difference in replacing the crystal. If the mirrors are dielectric coatings on the crystals, you're better off just getting a new laser.

 

[diachi]

Is yours integral mirror or external mirror? Makes a huge difference in replacing the crystal. If the mirrors are dielectric coatings on the crystals, you're better off just getting a new laser.

I'd hazard a guess that the coatings are on the crystals, at least for the vanadate. The aluminium piece just in front of the pump diode probably contains a lens to focus the beam into the vanadate. It could have a mirror in it too but I doubt it.

 

[ultimatekaiser]

Actually it looks like the driver is damaged. if you'd like, I can offer to give it a rundown and replace parts that are going bad. It looks like there's a cripsy tantalum cap on top that is getting rather crispy, probably from reverse polarity.

edit: btw, i hope you haven't messed with the OC or else that laser is gonna potentially be hard to mess with. they're oriented very precisely. but those crystals can withstand powers far beyond what that little diode can handle. they're not likely harmed.

 

[ultimatekaiser]

Sorry to bring this up again and necro, but did you ever get this fixed?

 

[styropyro]

Nope I was never able to get it to run. I put a lot of time into it too. It looks like getting another Nd:YVO4 crystal with mirrors coated for the right wavelengths is more money than a flat out new laser...

 

[Deleted member 16589]

Are you sure its not the driver did you ever replace the burned tantalum cap.

 

[ultimatekaiser]

Nope I was never able to get it to run. I put a lot of time into it too. It looks like getting another Nd:YVO4 crystal with mirrors coated for the right wavelengths is more money than a flat out new laser...

I highly doubt you need a new crystal....and yes they probably are. But n all seriousness, I can likely fix it for you pretty easily, both the tantalum (if needed) and the alignment. I just restored two other CNIs recently and already have the stuff out if you're interested.