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Experimentonomen

Mon Jan 11 2010, 06:19PM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

I got a new toy today, a baby Nd:YAG laser module.

Few pics:
001

Theres also a video:

...

Mon Jan 11 2010, 06:48PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Looks good!

A few comments-
Be careful overdriving the laser while it still has its original q-switch; they will fry with much more than 20j of input energy. They aren't that hard to remove, although it can be a little nerve wracking, but especially if you have already fried it and are not concerned about scratching it it is only a matter of unbolting the reflector assembly, removing the screw that holds in the yag rod, and using a screwdriver or other rod to force it out of the reflector assembly. If you want to keep it in tact, you can use a small drill bit and/or razor blade to remove the glue holding it in, and pressing it out with a smooth rod covered in something soft.

You are still left with an OC that has a too low a reflectance for optimum operation (its only about 20% reflectance!), but you will still get a bit more power. I am working on finding the optimum reflectance for the OC for these lasers, I expect that ~80% reflectance will give the highest output energy.

Also, adding a focusing lens to the laser (1-5cm are good focal lengths, shorter than that and you vaporize your lens, longer than that and you don't get a very small spot size) will make the laser a bit more fun to play with

. If your q-switch is still working, adding a short focal length lens to the output will result in air ionization!

Also, make sure to wear goggles! The beam may be invisible, but its still exceptionally dangerous!

Experimentonomen

Mon Jan 11 2010, 07:00PM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

I cant see any Q-switch:-? I thought those were active units similar to an acousto-optic modulator.:-|

Yes i know that 1064nm IR is as dangerous as visible lasers if not more so, just the stray light from the flash lamp stings a bit in the eyes.

I thought of adding a lens, but then iÂ´d like to add a aiming laser too so i can see where the focal point is.

If there is a q-switch in there, i dont give a shit if i fry it or not.:-p

Z28Fistergod

Mon Jan 11 2010, 11:48PM

Registered Member #2040 Joined: Fri Mar 20 2009, 10:13PM
Location: Fairfax VA
Posts: 180

You really should be wearing goggles with that thing.

The qswitch is passive; it is something called a saturable absorber. It will absorb some of the laser's energy before it becomes "saturated" and will then let the light pass through. What it's good for is blocking the reflecting mirror, thereby preventing large scale stimulated emission and allowing a larger population inversion. Then once it's threshold is reached the qswitch passes the lasing wavelength so the photons can be reflected within the cavity and amplified. The larger population inversion produces a relatively short pulse with a high peak power.

Experimentonomen

Tue Jan 12 2010, 02:20PM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

Today i decreased the capacitance of the capacitor bank to 117.5ÂµF so now the peak energy to the lamp is around 25J rather than 120+J, i also added a PFN and a lens so now in the focal point of the lens i get a bright blue speck when the laser fires.

Unfortunately this speck is too short lived for the camera to see it :(
A vid:

...

Wed Jan 13 2010, 07:15AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

It is indeed tricky to capture events that are only a few ns long, I have had good luck with setting my camera for a ~1s exposure, and firing the laser in a dark room. The flashlamp illuminates the scene, and the resulting air ionisiation and/or fireball is quite stunning.

Experimentonomen

Wed Jan 13 2010, 04:04PM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

Heres a frame from the video, shows the ionized air in the focal point and the fireball shooting out from the battery which is a few millimeters beyond the focal point:
NdYAGlaserfires

Earlier tody i made the yag battery driveable by putting a coilgun booster charger in the cap box:
001

The pfn:

Connections:
003

My crude triggering device:
004

...

Wed Jan 13 2010, 04:40PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Very nice!

Do you have any other plans for it, other than removing ink?

Experimentonomen

Thu Jan 14 2010, 08:24AM

Registered Member #941 Joined: Sun Aug 05 2007, 10:09AM
Location: in a swedish junk pile
Posts: 497

Strictly a toy, no plans.

Hazmatt_(The Underdog)

Thu Jan 14 2010, 11:03AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

How about tattoo removal hahahha OUCH! hehe

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