Old 04-02-2015, 11:34 AM #1
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Default DPSS green vs diode-based module building cost?

I had to come back to this question again.

I wanted to build both red, green and blue laser "on/off" modules (not pointers, not handheld) as powerful as I can and add them to my collection of laser stuff.

With blue I could get as high as 10W with newer mutlimode diodes and knife edging and beam correction prisms. The cost of the blue diodes was good.
Compared to blue DPSS's 3-5% efficiency it was obviously the only good option for me.

Red was less cheap and powerful, but the same method used with longer array worked.
Compared to red's DPSS conversion efficiency it was also a better choice.

Now with green it's a bit harder. I could use the same knife edging and beam correction, but the cost of the green diodes is more than 10x of the reds and blues ($400 just for a 1W diode).

So I'm thinking maybe going with the DPSS road would be more cost effective for the green.
All I know now is
1)temperature has to be controlled,
2) I need a Nd:YAG crystal to convert the 808nm to 1064
3) I need a KTP crystal to convert the 1064 to 532nm which I need.

What I don't know
1) How do you choose which Nd:YAG and KTP to use? Do the types depend on the pump diode's power?
2) How are they positioned (distance from pump diode to Nd:YAG and from Nd:YAG to KTP?
3) More info about temperature control. What's the temp needed?

I'm thinking of using a 20W pump diode and getting a 5-6W green beam. The red and blue have less perceived brightness, I'm sure the 3 beams will look nice and epic together if the green is weaker.



Last edited by iroquois; 04-02-2015 at 11:36 AM.
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Old 04-02-2015, 04:22 PM #2
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Default Re: DPSS green vs diode-based module building cost?

Quote:
Originally Posted by iroquois View Post
I had to come back to this question again.

I wanted to build both red, green and blue laser "on/off" modules (not pointers, not handheld) as powerful as I can and add them to my collection of laser stuff.

With blue I could get as high as 10W with newer mutlimode diodes and knife edging and beam correction prisms. The cost of the blue diodes was good.
Compared to blue DPSS's 3-5% efficiency it was obviously the only good option for me.

Red was less cheap and powerful, but the same method used with longer array worked.
Compared to red's DPSS conversion efficiency it was also a better choice.

Now with green it's a bit harder. I could use the same knife edging and beam correction, but the cost of the green diodes is more than 10x of the reds and blues ($400 just for a 1W diode).

So I'm thinking maybe going with the DPSS road would be more cost effective for the green.
All I know now is
1)temperature has to be controlled,
2) I need a Nd:YAG crystal to convert the 808nm to 1064
3) I need a KTP crystal to convert the 1064 to 532nm which I need.

What I don't know
1) How do you choose which Nd:YAG and KTP to use? Do the types depend on the pump diode's power?
2) How are they positioned (distance from pump diode to Nd:YAG and from Nd:YAG to KTP?
3) More info about temperature control. What's the temp needed?

I'm thinking of using a 20W pump diode and getting a 5-6W green beam. The red and blue have less perceived brightness, I'm sure the 3 beams will look nice and epic together if the green is weaker.
You will need to do a lot of reading to understand how frequency doubled YAG/YVO4 systems work.

Start here: Sam's Laser FAQ - Home-Built Diode Pumped Solid State (DPSS) Laser

It's not quite as simple as just dumping 20W of 808nm into a piece of YAG, passing the 1064nm through some KTP and then getting 5W of green out of the other end.

Using bonded crystals could reasonably get you to ~0.5W with little effort, past that is when things start to get more complicated. How are you going to pump it? Side pumped YAG, Fibre pumped YVO4? What cavity design will you use, linear, L-Fold, Z-Fold? What mirrors will you use, planar, spherical (What radius)? You'll also need to pick the right YAG/YVO4 for CW pumping, the amount of Nd doping makes a huge difference, possibly machine mounts for them + the KTP depending on how you go about it.

Not trying to discourage you, just trying to show you the challenges involved in such a project. There's a reason you can't buy 5W of 532nm for anywhere near as cheap as 445 or 462.
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Last edited by diachi; 04-02-2015 at 04:25 PM.
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