Re: Pulse laser
Forty, Fri Aug 03 2012, 02:04PM

I believe xenon flash bulbs can be used to pump a laser. Since the xenon doesn't lase itself, if you focused it you'd just have a focused flash of light (which can still burn stuff but only at the point that it's focused to)

Goldmine has a few cheap crystal laser rods that I think can be used to make your own pulsed laser if you set it up right (probably needs mirrors and a q-switch, I'm not too experienced with building them)

Re: Pulse laser
Daedronus, Fri Aug 03 2012, 03:23PM

Depends on how much patience and luck you have, I got nd:yag medical laser modules, flash lamp pumped as cheap as 150$ (+shipping).

Check out my youtube channel...

PS: stay away from anything that is not nd:yag, like erbium or holmium, finding resonator mirrors for them is a big PITA

PPS:

I'd make a best offer for 150$
I'm guessing this is a nd:ce:yag essentialy it's nd:yag, same lasing line, 1064nm

Re: Pulse laser
Shrad, Wed Aug 08 2012, 12:46PM

go for passive Q-switch like Cr4+:YAG plus Nd:YAG, or bonded Cr4+:Nd:YAG

Re: Pulse laser
Legit_bacon, Thu Aug 09 2012, 05:54AM

Thanks for replies all, unfortunately i don't have upwards of $250 Nzd to blow on a project... So might have to sideline this idea. Defiantly look into it when my fiances are healthier :D

Re: Pulse laser
Carbon_Rod, Thu Aug 16 2012, 06:41AM

US customs will sometimes seize/bounce imported lasers over 5mW, and prohibit surplus headed out of the country. Note medical devices need transport certificates, but surplus junk does not... a common ebay scam with "no refunds" offered for an item that can't be shipped....

Typically, some use five solid state diode laser stacks in a pentagram mirror cavity to pump high power rods. This is usually not consumer level hardware, and if any optics are out/dirty it fails catastrophically.
Yet they are now often available in the lower range 50W to 500W products:


Note, a YAG rod with its end reflector cup assemblies intact/aligned are cheap, and driving it to the crystals physical limits should be trivial. Mostly the cheap surplus "bare" rods are from old obsolete low power range finder technology.

Personally, I think the room-temperature solid-state maser is a more interesting technology.



Perhaps a better description of what you are trying to build may yield viable options.
If the lifespan of an Arc flash tube is acceptable, it may be a cheaper option....

Re: Pulse laser
Sigurthr, Thu Aug 16 2012, 01:39PM

Heh, I remember that thread >.>
(I designed the pulse circuit the OP ended up using.)

Nd:YAG alignment is a bitch, but it certainly can be done. Do try for rods with built in mirrors though, as it greatly simplifies things.

An aspect that needs consideration when looking at making your own YAG (or Ruby) laser is cooling. The rod and lamp are going to get HOT... FAST, and need active cooling. Water cooled flash lamps are common, but it isn't as easy to cool a laser rod, so DIYers usually wind up keeping the pulse rate quite low to compensate.

Btw, you can easily pulse a CO2 laser system, and they are MUCH cheaper and easier to find. IIRC SSY-1 systems run around $600 for a working complete unit, you can get a brand new CO2 tube +power supply (honestly if you're on this forum though you could probably build one yourself though) for <$400.

I've got long standing plans to grab one of those $100 chinese CO2 tubes and build a psu from my SGTC's old NST using the old MMC as a filter cap, and some cheap HV diodes for a full wave rectifier.

Re: Pulse laser
Pinky's Brain, Thu Aug 16 2012, 02:24PM

Why can't you put everything under water? It's has good transparency in UV and visible wavelengths and it's a good insulator at short pulse lengths.

Re: Pulse laser
Daedronus, Thu Aug 16 2012, 10:35PM

IMHO medical heads are far from obsolete or low power.
Perhaps they are obsolete from a medical point of view but the power is there.

and they don't get hot THAT fast without water. not to mention most, like the one I linked, have water ports, and the flash lamp is fully isolated from the water, you can just use tap or distiled water !

SSY1 is junk, it's small, it's low power.
You can get a medical grade head for 150-250$ + mirros 70-80$ + mirror holders 80$
Add a power supply and some kind of mounting rail and your done.

And,
I never had any issues with the customs importing medical grade laser heads.

Re: Pulse laser
Legit_bacon, Sat Aug 18 2012, 01:03AM

Im sorry i think theres a bit of misunderstanding as to what im wanting to achieve. This was the origional video i watched and was hoping to find a cheap way to build something similiar but lower power. Unfortuanatly due to some unfortuante curcumstances involving my smart phone i have no money for projects at all :(

Re: Pulse laser
Yandersen, Sun Mar 03 2013, 07:37AM

I was playing with high voltage discharges through air in a last few weeks and I come to this idea which I hope, may work as kinda gas laser:


So the idea here is to use a strong magnetic field created by a long cylindrical axially-wound air-core coil to compress the discharge arc into a thin plasma wire and push it right into the center of a discharge chamber, aligned with a hole through which the majority of light is supposed to go out.
The benefits of adding the coil, as I understand, will be the prevention of contact between plasma and chamber walls (so only electrodes will get hot), increase of ion density in the discharge path (the number of ion collisions will be higher), increase of light emission along the output line.
What do you think?

I am preparing my soul to build that thing easy-way - without mirror glass pipe, chamber not sealed, using just an air in a discharge, ~5mm between electrodes, connecting coil in series with electrodes and power it all from 16J cap (750V) pulsing the HV to ionize air to trigger the discharge.

Re: Pulse laser
Daedronus, Sun Mar 03 2013, 05:35PM

I think argon lasers already use external coils around the discharge channel like you suggest.

Re: Pulse laser
Yandersen, Sun Mar 03 2013, 05:52PM

Seriously? So my thing may work?
Any links to tech articles which can help? Any numeric insight possible?

Update: no success; homemade laser didn't worked - just a bright pulse flashlight at most. 600A at peak, 150us pulse.

Re: Pulse laser
Yandersen, Mon Mar 04 2013, 10:00AM

Is it actually possible to make a pulse laser from scratch? Say, take a glass tube, fill it with CO2 for example, put a mirror at the end and electrodes and discharge couple hundreds of joules of HV through that? Would it work? Or it will simply blow like a grenade?

Re: Pulse laser
Daedronus, Mon Mar 04 2013, 11:09AM

Sorry, I don't know much about argon laser, I just remember some of them use coils or permanent magnets.
For coils I think they just use the main power supply, basically, the coil is in series with the arc discharge.

I really don't see why a diy pulse gas laser it would not work. This has been done before.
But for a CO2 you need more then just CO2. You could try a low pressure longitudinal N2 laser, this was also done before.

Re: Pulse laser
Shrad, Mon Mar 04 2013, 01:10PM

CO2 will be easy to make, but plain air or N2 will need shorter than 20ns discharge time and low, REALLY LOW inductance path

your setup is close to a longitudinal excitation laser, so there might be plenty of documents on the net

you will need vacuum though

Re: Pulse laser
Daedronus, Mon Mar 04 2013, 02:18PM

Edit: scratch that
"The upper-state lifetime of nitrogen is inversely related to pressure; it is approximately 40 nsec at pressures of a few Torr, decreasing to perhaps 2 nsec at 1 atmosphere"

From:


And, check this out:

Re: Pulse laser
Yandersen, Mon Mar 04 2013, 08:09PM

Oh, thanks, great resources!
Now I'm convinced that homemade laser from scratch is a waste of time. Seems like just a single high energy (xxxJoules) pulse discharge for at least a dozen of microseconds long is not smg acceptable for laser operation even if it is a single pulse. Am I wrong?

Re: Pulse laser
Daedronus, Mon Mar 04 2013, 11:04PM

For N2 laser the problem is the relaxation state, it has a long life time, so after the N atoms get excited then relax/emit the laser light, they are in a state where they can't contribute to the lasing and will absorb the laser light.

That is to say N2 lasers are self quenching.

However, this is not the case with Co2 lasers, you can dump as many joules as you want, even in mili seconds.

Not all is lost with N2, you just need the joules to be at very high voltages (so C is small).
But don't expect too much, I have never seen a N2 laser to do a lot of damage.

TEA CO2 laser are completely different beasts, they can do LOTS of damage.

The easy mode high damage laser is of course the nd:yag.

Re: Pulse laser
Shrad, Tue Mar 05 2013, 07:49AM

N2 lasers can be pretty powerful, you just need to get to a few Torr as you said, and use an unstable resonator like those VLS337 cartridges

if you need power easily, the way to go is the CO2 laser, either TEA or LE

CO2 laser is quite easy as you can find CO2 dirt cheap and circulate through the cavity at atmospheric pressure without spending a kidney per pulse with special gas mixes

Re: Pulse laser
Yandersen, Tue Mar 05 2013, 11:36AM

But I need special beryllium output glass as well as precise mirror adjustment - regular glass or plastic is opaque for IR. In other words, for CO2 laser setup I need to buy the actual pipe at least (if I do power part on my own).

Re: Pulse laser
Daedronus, Tue Mar 05 2013, 11:50AM

Beryllium is not used for co2 optics.

Instead the usual choice is ZnSe (zinc selenide)

The high reflect mirror is usually gold coated plain glass.

ZnSe is not that expensive:

Re: Pulse laser
Shrad, Tue Mar 05 2013, 12:41PM

there are plenty of used optics out there, and you can also use a polished copper plate for the HR and a polished copper cup with a small hole in the middle for the OC part, in a hemispherical unstable cavity, as it should have enough gain to be able to lase with only tens of passes

Re: Pulse laser
Yandersen, Tue Mar 05 2013, 09:52PM

Wow, $60 for a tiny piece of colored glass? For me it is expensive.
Anyway, in general, did anyone here succeed with pulsing a dozen of joules of output energy in a single pulse shot? I can do it in a way of kinetic energy of iron projectile with recuperational gauss at 20% efficiency and under $200 of total part cost, but if the same damage can be done by laser - sure it is much more cool and worth the effort even if it will cost some more. Any hope?

Re: Pulse laser
Daedronus, Tue Mar 05 2013, 10:08PM

I can put a hole in 1.7mm of steel in 2 pulses:


But that is probably not dozens of Joules.

As Shrad said, you can get creative....especially with gas lasers.

Re: Pulse laser
Shrad, Wed Mar 06 2013, 08:08AM

this is an output coupler, you will need this if you want some power



this is a HR mirror you'll also need



and this is a borosilicate tubes set you'll need for the cavity to be pumped down, along with its water channel



after that you have to turn some mirror holders which will be your cavity endcaps, electrodes and tube mounting ends (two tubes concentric for cooling water flow, and ports for water and gas)

you'll have to design them to be able to adjust the mirrors orientation by a certain amount

this is achievable with a budget of $200 to $400 except the power supply which is quite simple to make (30kV max 10mA max)

there is also the TE or TEA CO2 laser which is the same as a TEA N2 laser except you flow some CO2 between electrodes... total budget can be less than $100 for this one