Short Length Large Diameter ND: YAG Crystal - What for?

[RedCowboy]

The peak pulse energy may be high, but the duration of the pulse is so short and the pulse rate is so low, 50-100 hertz would be nice, now that big medical unit photonicinduction had was a 100w CW, it must have had a very high pulse rate, but it was so large, much too large for a HH.

You can hear this one working, still it's pulse width is so short, the saving grace is it could be tightly focused, I wonder how well over distance?
I have seen TEM00 advertised on some of these tattoo removers.

Alaskan posted these photonicinduction videos before, but here's the teardown for anyone who hasn't seen it. https://www.youtube.com/watch?v=jOkZCydRHBw

 

[ultimatekaiser]

The one I saw PI take apart was CW it's not pulsed. It has CW krypton arc lamps iirc. A friend of mine had one of those hundred watt ones, but a lamp cracked.

 

[RedCowboy]

I knew we could pump YAG with an 808nm LD steady on/CW, but thought white lamps needed to be Q switched for other than Giant wave formation.

I would rather run CW, what size in watts would that lamp need to be?

 

[diachi]

I knew we could pump YAG with an 808nm LD steady on/CW, but thought white lamps needed to be Q switched for other than Giant wave formation.

I would rather run CW, what size in watts would that lamp need to be?

Q-switch is part of the cavity, nothing to do with the lamps.

Yes, you can use arc lamps with YAG instead of flash lamps - all watercooled for both the lamp (s) and the rod.

Lamp size depends on how much power you want and a bunch of other factors.

 

[RedCowboy]

Interesting reading.

https://en.wikipedia.org/wiki/Q-switching

 

[ultimatekaiser]

Yeah I have an old style mechanical q-switch in my ruby laser. Newer AOM ones are nicer, but didn't really exist at the time.

 

[Alaskan]

In that tattoo removal machine video, I wonder what is inside those three heads? The 1064nm just optics, the 532nm a KTP or LBO crystal and optics together? If so, how does that work, no heater wires to keep the crystal at a sweet spot temperature.

 

[ultimatekaiser]

It's not doubled. But if you were to do so, it's usually done by a KDP or similar to avoid damage, which would be held in a high temp heatsink with a tec or cooling plate of some kind. Since these would be typically short duty cycle, it wouldn't get all that hot.

 

[RedCowboy]

The 532 head is a little longer, I suppose it has a KTP and lens, there could be a TEC in the wand.

I read a lot of these Chinese tattoo mchines have a 300,000 - 600,000 pulse count until reduced output.

 

[ultimatekaiser]

That sounds logical. Most long-life low repetition, lamp driven lasers operate at about 10-20% of the explosion energy, which offers well over 100K pulses usually. My ruby only has about 7K on it, and the lamps have little to no sputter or ablation at all.

 

[Alaskan]

My take from the video is the green head is to output 532nm so it must have a crystal in it, put the gold colored one on and you get just 1064nm. Just didn't expect to be able to use a crystal without a TEC on it for the output of a YAG. One of the reasons I am interested in this is that is what I would like to do with my little ND:YAG but didn't believe it possible to run that way with consistent efficiency. Maybe it isn't consistent efficiency with these cheap tattoo removal machines.

 

[paul1598419]

That sounds logical. Most long-life low repetition, lamp driven lasers operate at about 10-20% of the explosion energy, which offers well over 100K pulses usually. My ruby only has about 7K on it, and the lamps have little to no sputter or ablation at all.

I am so envious of you and that ruby laser! Even with a mechanical Q switch, it is beyond cool to me.

 

[DashApple]

I knew we could pump YAG with an 808nm LD steady on/CW, but thought white lamps needed to be Q switched for other than Giant wave formation.

I would rather run CW, what size in watts would that lamp need to be?

I had the exact same laser , pulled around 28A / 230V for 80W optical .

The lamps run CW hence why there is water flowing over the entire lamp including connections at each end

0011 by TwirlyWhirly555, on Flickr

 

[RedCowboy]

LOL 6440 watts in for 80 watts out, that's 6360 watts of waste heat to get rid of, better keep the cold water flowing alright.

 

[diachi]

LOL 6440 watts in for 80 watts out, that's 6360 watts of waste heat to get rid of, better keep the cold water flowing alright.

That's part of the reason a lot of modern systems are going diode pumped, way more efficient.

Think that's bad? Large frame ions are worse ... actually, the smaller air cooled ions are even less efficient. My SP-163 pulls 1000W and does about 30mW out.

@DashApple - do you have any pictures of the inside of the pump chamber to show folk here? If not ... I'll dig something up!

 

[DashApple]

I have a few : D

This is the lamp that dose all the pumping .

IMG_1503 by TwirlyWhirly555, on Flickr

Not so good picture of the cavity and the YAG rod in its flow tube .

008 by TwirlyWhirly555, on Flickr

outer case of chamber , each end are the lamp connections .

006 by TwirlyWhirly555, on Flickr