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Homemade flash-lamp pumped lasers

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Adam Munich

Tue Oct 19 2010, 07:39PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
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What about liquid cooling the lamps? Put the laser under mineral oil along with a fan might prevent them from heating up too much.

Shrad

Tue Oct 19 2010, 08:09PM

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cooling such lamps is done with deionized water for large lasers

the lamps as well as the laser rod (encapsulated in an antireflection-coated tube) are surrounded by flowing deionized water, while the electrodes are being kept dry outside the pump chamber

latest devices use donut diodes though, where the diodes have circulating holes... you pile up several donut arrays to get a tube of say, hundreds of watts

search coherent nuvonyx on ebay and you'll find a kilowatt-rated array for a kilobuck-rated wallet (as well as the controller from the same seller... if I had the money... but it's the same for everyone I guess ;))

Daedronus

Wed Oct 20 2010, 03:01PM

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Deionized water should not be needed, if the electrodes are on the dry side and if you use series triggering (there are no trigger wires in parallel with the flash lamp).

The water has another important role, besides cooling, it filters most of the UV from the flash lamp.

The UV is not useful for pumping and it can actually degrade the nd:yag rod.

Pinky's Brain

Wed Oct 20 2010, 04:01PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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Oh that's a shame, can't really use 100s of ns range flashes with the xenon tubes then ... because that's nearly all UV. Will have to drive them with long pulses.

If you really want high intensity bursts without Q-switching wouldn't it be better to use a dye laser then?

Or alternatively, an amplifier setup ... but that's getting awfully complex.

Daedronus

Fri Oct 22 2010, 11:22AM

Registered Member #2329 Joined: Tue Sept 01 2009, 08:25AM
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That is one question that also got into my mind recently...

The fluorescent lifetime of the nd:yag is about 200us, so, from the moment you start putting energy in the rod, for the first 200us none should come out...unless you are also putting in 1064nm photons that will trigger a stimulated emission...but this should not trigger lasing, I think, because most of the photons from the flash lamps should be perpendicular, to the optical axis, so they are just robbing energy from the pumping process.

Now the actual question, if you finish the pumping process before the 200us pass, how long the output pulse will be?

I'm guessing it's not going to be in the nano second range as is the case if a q-switch was used.

Pinky's Brain

Fri Oct 22 2010, 02:11PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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Spontaneous emission is a stochastic process, there is no fixed fluorescent lifetime ... the moment the lasing threshold is reached it lases.

That's why you need Q-switching in the first place, or use the rod as an amplifier (you pump a rod without a lasing cavity, and then shine a laser through it).

Neuuubeh

Tue Nov 30 2010, 06:43PM

Registered Member #3411 Joined: Sat Nov 13 2010, 08:25PM
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Guys where do you get your flashlamps from? Especially for our german members, Id like to mess around a bit, but cant find decent stuff (on ebay at least, maybe i suck at searching) :/. Any tips for an online store or something

Pinky's Brain

Sun Dec 05 2010, 03:33PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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I have been searching for cheap quartz flash tubes, I didn't pull the gun on buying any and testing if they truly were quartz though. I have found two types of cheap flash tubes which are said to be quartz.

These are I think clones of old GE types. The original FT-218's were quartz at least, this guy made a ruby rod laser with them.

These seem to come from Russia. Only the IFK120 are said to be quartz, but I think the monster linear tube is as well.

Of course they could very well all just be borosilicate, so caveat emptor. If you do buy any, let me know :)

Adam Munich

Sun Dec 05 2010, 05:44PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
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It's easy to test if they are quartz; quartz is softer than glass. quartz is a 7 while glass is a 5.5. Orthoclase will scratch glass but not quartz.

Pinky's Brain

Sun Dec 05 2010, 06:15PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
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High temperature glasses are all harder than soda lime glass.

If you had a short wave UV lamp and some stamps which respond to it (varies per nation) you could test if the glass lets through short wave UV.

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