808 to 532

I have a handheld 5W 808nm IR laser. Since I can't use it without my NVG's I was thinking about adding a KTP crystal to make it green. Would this be worthwhile given the loss of mw through conversion or not?

3LEGGEDSQUIRREL said:

I have a handheld 5W 808nm IR laser. Since I can't use it without my NVG's I was thinking about adding a KTP crystal to make it green. Would this be worthwhile given the loss of mw through conversion or not?

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You may want to read up some more on how 532nm DPSS lasers work.

You can't just slap a KTP crystal into your 808nm beam and get 532nm. Even if you could use the KTP crystal directly with the 808nm beam it'd yield 404nm, not 532nm.

You need to pump Nd:YVO4/Nd:YAG with 808nm which then produces 1064nm (with the correct optics too) and then the KTP produces 532nm from 1064nm. Again - you need the correct optics for that part too.

There are no "hybrid crystals" (Crystals that have the correct HR/OC mirrors on the faces and contain both YVO4/YAG and KTP) that can take a pump input of 5W. At least none that I'm aware of - the largest hybrid crystals I've seen go up to around 0.5-1W pump power.

That leaves you with using individual crystals with externally mounted HR/OC mirrors - although sometimes having the HR mirror coating on the YVO4 is possible. You won't have much success pumping that with a handheld.

You'd be looking at a setup like this:



Although both the HR and OC mirrors are external to the crystals in that setup.

May want to rethink your idea and just buy a 532nm laser...

As diachi said, it isn't that easy to do.

I was going to post something similar but didn't know you're background and if you've had experience building DPSS units so I stayed quiet. 532 DPSS is one of the more efficient processes around, but it isn't as easy as slapping crystals and voila! You need them aligned etc...

-Alex

Hap said:

532 DPSS is one of the more efficient processes around, but it isn't as easy as slapping crystals and voila! You need them aligned etc...

-Alex

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Well, you can do that with hybrid crystals - I've done it holding them between my fingers and hitting them with 1W 808nm from a handheld.

That said - it's not at all stable/reliable - for obvious reasons. You'll get a decent amount of green for a few seconds at most I've found. Can hardly be considered useful for anything. Plus without any other optics the output is highly divergent. We're talking >10mRad.

As I said above - there's no hybrid crystals that will handle 5W that I'm aware of. They're all too small so you'd end up damaging them, either they'd crack or you'd burn the coatings.

So yes, for all intents and purposes you're correct Hap.

diachi said:

Well, you can do that with hybrid crystals - I've done it holding them between my fingers and hitting them with 1W 808nm from a handheld.

That said - it's not at all stable/reliable - for obvious reasons. You'll get a decent amount of green for a few seconds at most I've found. Can hardly be considered useful for anything. Plus without any other optics the output is highly divergent. We're talking >10mRad.

As I said above - there's no hybrid crystals that will handle 5W that I'm aware of. They're all too small so you'd end up damaging them, either they'd crack or you'd burn the coatings.

So yes, for all intents and purposes you're correct Hap.

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Haha!

Imagine trying to build a 589 now

-Alex

Thanks for the info guys. Im new at this and the info provided was helpful. Im still learning.

Hap said:

Haha!

Imagine trying to build a 589 now

-Alex

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Nightmare fuel... At least it's a bit less picky than 593.

Thanks for the info guys. Im new at this and the info provided was helpful. Im still learning.

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Most welcome - if you're looking for more information on DIY DPSS this page has a good chunk of information: Sam's Laser FAQ - Home-Built Diode Pumped Solid State (DPSS) Laser

Thanks for the link to Sams page on DPSS diachi. I do currently own:

2W WL 445nm Spyder III
1.4W WL 445nm Spyder III
750mW WL 532nm Spyder III
5W FMA 808nm

I have a few more (noname) specimens along with a DBAL A2 on my SCAR 17.

I have no experience in building them, but I am amazed at those who do and I am grateful for this forum and those who are willing to help. My expertise lies elsewhere.