What exactly do you mean?

[NightExplorer96]

I was reading a couple of threads lately about the different DPSS wavelength's and how some are harder to align than others.

My question is: What exactly do you mean by aligning? I.e, isn't 532nm just as easy as 473nm to align, since you just have to put the crystals in a line(straight).

Im positive I have it wrong, but just trying to learn!
Thank you for the help.

 

[Marco Polo]

IIRC alignment comes into play in a bigger way when it's something like a 593nm or 589nm sum frequency generation DPSS. Those processes involve colliding two different photons of different energy to obtain the desired wavelength, and I believe that the angle at which they collide is extremely important to making it work right. It's part of why the yellow pointers tend to be unstable (and/or put out green) compared to "simple" DPSS like 532nm or 476nm. And of course even those examples require the crystals to be lined up properly, hence their relative instability versus a direct diode. But apparently SFG is even more sensitive to things being out of place.

That is my understanding of it, but I'm sure others here can explain it better than I can :beer:

 

[Blackwolf]

Polarization is important too http://laserpointerforums.com/f45/do-yourself-complete-green-dpss-o-like-crystals-42495.html
see first image

 

[Blackwolf]

isn't 532nm just as easy as 473nm to align, since you just have to put the crystals in a line(straight).

532 is easier than 473 not because of alignment as much as the other things you need to take into account about the crystals.

532 473 and 671 are all the same process and are aligned in similar ways 473 is more difficult because the crystal needs to be temperature controlled and sealed from moisture. Since 946 is a weak line and lbo is not transparent to 946 more power needs to be applied at the pump end. for the lower power pointers the 808 diode needs to be pulsed to push the crystals past their lasing threshold. (imagine an ebay green pen. if you put in a 10440 lion3.7v say you get 60mw then you put in two NiCd batts2.4V and it doesn't lase at all). If you had a 473 crystal set and properly controlled the temp you could get some nice lasing.

here is a great video of a DIY 473 DIY 473nm Blue Laser / Test 2 60mW - YouTube

 

[BShanahan14rulz]

low power crystals are aligned, bonded, and cut out, so that it basically looks like two crystals glued straight to each other with no rotation.

 

[NightExplorer96]

532 is easier than 473 not because of alignment as much as the other things you need to take into account about the crystals.

532 473 and 671 are all the same process and are aligned in similar ways 473 is more difficult because the crystal needs to be temperature controlled and sealed from moisture. Since 946 is a weak line and lbo is not transparent to 946 more power needs to be applied at the pump end. for the lower power pointers the 808 diode needs to be pulsed to push the crystals past their lasing threshold. (imagine an ebay green pen. if you put in a 10440 lion3.7v say you get 60mw then you put in two NiCd batts2.4V and it doesn't lase at all). If you had a 473 crystal set and properly controlled the temp you could get some nice lasing.

here is a great video of a DIY 473 DIY 473nm Blue Laser / Test 2 60mW - YouTube

Thanks Wolf! Jeez, I knew 473nm was much more complicated to produce than 532nm for some reason, but never expected it to be this complicated.

Those guys who make 473nm lasers sure are experts

 

[trencheel303]

Thanks Wolf! Jeez, I knew 473nm was much more complicated to produce than 532nm for some reason, but never expected it to be this complicated.

Those guys who make 473nm lasers sure are experts

You think that's bad? You want to try 593.5 on for size.

It goes something (very roughly) like this:

An 808nm pump diode fires a crystal that simultaneously lases at 1064nm and 1342nm (which is not easy to start with), these are then summed and passed through KTP, IR filtered and collimated and that's what gives you the yellow line. The 1064 and 1342 can also be doubled and that's why yellow pointers occasionally give off green and red.

Harmonics in general interests me as I'm also a bit into radio, particularly the anomalies like receiving AM radio stations on a second or third harmonic (I think I've done this by accident before). DPSS essentially makes use of this same principle by taking IR light, and then converting it into a different colour by using the second harmonic frequency generated by the coated crystal. I think this similarity is one of the contributing factors that got me interested in lasers.

Pretty head melting stuff to be honest, especially as I can't grasp math very well.