Tweaking a He-Ne laser.

[Meatball]

^^Hey yeah, that sounds about right. To get a stable output of some of your more "non-red" lines, you'd need a larger bore diameter and a lower (I think lower) Neon to Helium ratio.

I think that's how a tube is made to bust out some of those yellows and greens.

 

[Solonar]

That particular tube will never output more than about 1.6mW. It was only designed for 1mW in 1985 when I was building them( only about 1% of them ever got to 1.6 mW).

If you look closely when the laser is off, you can see the ~0.5mm bore that the arc travels through to generate the gas plasma.

The different wavelengths are generated with different pressures, slightly different gas mixes and different optics.

the IR tubes used a higher pressure and glowed a deeper red, while the greenes used a lower pressure and glowed a bluish pink.

 

[james1095]

Yeah I didn't mean to imply that you'd get other wavelengths out of a little barcode scanner tube. The tubes I've managed to do that with were all over a foot long and the only one that did it all that well was a yellow one.

At least 99% of HeNe tubes under about a foot long are red. There just isn't enough gain on the other lines. A 2mW green tube is the same physical size as a red tube that would produce 10-15mW.

 

[butthead]

Thanks for all the replies, I have surely learned some more to say the least.
It's not easy to make a good DIY laser, especially because the required hardware is not easily available over here. And I've also seen that certain suppliers in the US do not export stuff due to BLABLA export regulations.:yabbmad:

Think I'll just stick to solid state for the time being .

And oh, here's the clip what initially made me enthusiastic.

 

[qumefox]

For me, the amazing part about that video isn't the laser. It's the photography. It takes some pretty sophisticated equipment to time the taking of the photograph with the laser pulse. Well, sophisticated from a hobbyist standpoint anyway.

 

[james1095]

You can get some impressive photos by taking a long exposure. So long as nothing in the scene is moving, set the camera to hold the shutter open for several seconds then fire the laser. I was playing with my brother's DSLR and was able to get some neat effects. While not laser related, one of these days I need to build a triggered strobe with adjustable delay so I can take some stop action photos using the same technique.