Covert 808nm to 532nm HELP!

[GooeyGus]

Yes align at full power. Also, make sure your first crystal is facing the right way. Make sure there is a clear optical path through both crystals to the diode.

Also, does your diode output a square beam or is it more like a line? The square beam means the diode is fast axis collimated, which I suspect your laser will require to run properly. Without the fac lens it will be hard to get enough energy density in the vanadate for good lasing to happen.

[AlexGe]

Yes, the diode output a square beam.
Take luck at this picture please: http://picasaweb.google.com/alexge19...88523955897602

There is a small scratch on crystal surface, could it be damaged?

[GooeyGus]

Hmmm that scratch doesn't look good. What did you use to wipe the surface of the crystal?

[AlexGe]

The surface was wiped with 96% Alcohol and soft cotton wool. I did the scratch accidentally. Between laser diode and crystal is a small aluminum ring witch keep at distance the crystal from diode. One time I have forgotten to put this ring and the crystal touched the diode.
You can see it on this photo: http://picasaweb.google.com/alexge19...70974130750402

[shrad]

please, never align at full power!

this will ruin your eyes if you don't use protection goggles !!! 1W of scattered 808nm, 50cm away from the diode, will burn your retina

alignment of DPSS lasers like this one requires:

1: placing the YVO4 (first one) to obtain max power at 1064, with a powermeter
2: placing KTP (second cristal) and adjusting to obtain max power of 532nm
3: adjust output coupler to maximise output power, and repeat step 2 and step 3 to achieve highest power

be aware this could take you hours or even a pair of days of work if it is your first alignment job

[GooeyGus]

I always align at full or close to full power when the alignment is way off. Especially on lower gain lasers, such as 473... 532 is a bit easier, but the more pump power you have the more likely you are to get a little flash of green, even if the alignment is still a bit off.

It just makes things a whole lot easier because you're more likely to hit a 'sweet spot' and get a flash of green.

Obviously one must be very aware of the amounts of coherent light he is dealing with, but at long as you wear goggles and/or be very careful and mindful of where that light is going, it's really not a big deal.

Sure you can align at lower power, but what if you're just below the threshold of the yag/vanadate and you've passed perfect alignment a few times without even knowing it because you're not lasing on 1064 yet? That is a huge pain in the ass.

That's just my .02

Oh, also, when you are cleaning optics you should really always use a lens tissue that is safe for optical components. Cotton is nice, but it can hold tiny pieces of crap that you wont see, that can easily scratch the surface of these components.

You may need to get a new piece of vanadate, or raise your piece slighly so you are not trying to lase through that scratch. Good luck! That one looks like a doozie....

[AlexGe]

Thank you for your care.
Take luck at this picture please: http://picasaweb.google.com/alexge19...88523955897602 could this crystal be damaged?

The original laser was 150mw green from SPOOKY Blue V3. Now I use 1000mw 808nm laser diode. I don`t know what will be final 532nm power.
1 The YVO4 crystal is fixed, I can move + - 1mm left and right but can`t change focus distance.
2 With second one I can move + - 1mm left and right and also to change focus distance (+ - 1mm).
3 The coupler: I can`t change focus distance for this crystal. I can just rotate it. http://picasaweb.google.com/alexge19...70970392603234

[AlexGe]

I started this "epic" because the original laser works for about 8 moths, 5h each day and the beam of light became increasingly weak. The documentation says that it should be enough for 10000hours. OK. I said; may be this laser wasn`t a good quality made. I bought another 300mw laser(something like this: http://cgi.ebay.com/300mw-532nm-green-laser-diode_W0QQitemZ170340882753QQcmdZViewItemQQptZLH_D efaultDomain_0?hash=item27a91b9941&_trksid=p3286.c 0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1 205%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50). The seller says that it should work 10000 hours without problem. 2000Hours of working and the beam became very think.
I think it is more economical to buy just diode and do not spend money for pieces witch I already have…. But here is the problem… I don`t have light power meter...I don`t have a wave length meter…and so on... I “kill” already one 500mw 808nm …..About YVO4 crystal I think also was “killed” by me.
(

[ElektroFreak]

Building or performing massive repairs to DPSS lasers is a challenge to say the least, but it's extremely rewarding to see the end results. It takes a patient hand and good eyes and a little experience to get good results, however. If your just starting to consider repairing your own DPSS laser, expect a tough time of it at first and expect some broken parts. Also, a home-built or rebuilt DPSS laser will rarely see anywhere near 10,000 hours especially if you're new to building/repairing lasers.

If you're looking for longevity, spend the extra time and money finding a quality commercial unit. Go with brands like CNI or laser-wave. Both have excellent reputaions and stand behind their products.. I know it will cost some $$ and it won't be DIY, but IMO it sounds like you need a quality unit that won't let you down. If that's the case, buy a commercial unit from a reputable company.

[GooeyGus]

I still bet that laser will work with that scratch, the performance may be effected, but I bet you can get SOMETHING out of it.

If the first crystal (closest to the diode) is off by even .01°, the laser probably wont lase. The first crystal and the output coupler lens (the one in the mount with the three holes) need to be perfectly aligned with each other. The KTP isnt quite as critical, and it should do it's job as long as the light makes it through, you can adjust for peak power once you get it going,

Just keep trying, you'll get it.

If you can, shine a green laser directly into the front of the laser. It should bounce off the back of the crystal closest to the diode. the beam that bounces back should overlap perfectly with the beam coming in, if that makes sense. Make sure the incoming beam is level and centered in the output coupler. Look for a second spot on the output coupler (this will be a reflection from the back crystal). Shift the crystal around until you get a perfect reflection back into the incoming beam.