HeNe wavelengths

OK... SO I was wondering.... Are HeNe tubes sealed BEFORE the HR and OC mirrors, or do the mirrors actually create the seal on the tube? The reason I ask, is because I was thinking about cracking the mirrors off of mine and seeing if I could find the correct mirrors for a different wavelength, just for something fun to try. The tube was cheap, I'm not worried about losing it. ANYWAY.... I know I've seen these in green and yellow, and I also know that they still light up 'red-ish white' on the inside when they are lasing at these wavelengths. So I took a diffraction grating up to my eye to actually see what wavelengths it was actually putting out. I was a bit surprised. Yes there was red green and yellow, but I was a bit surprised to see that blue was in there as well, yet I've never seen a blue HeNe. Maybe the blue light in there isn't actually coherent laser light, but a byproduct of the process? I was able to put the diffraction grating up to my camera lens and get some shots, they're pretty neat. Look off to the right of the tube to see the actual colors that the tube is putting off.

Hey GooeyGus,
I have a HeNe tube that lights up with a broken glass that protects
one mirror ( the mirror is still there and the Tube is still sealed).
The other mirror is pristine. It is a Metrologic 1mW glass tube about 5-7/8 " mirror
to mirror and about 1" in diameter.
I can give you the tube for free for testing your theory. I can't see busting up a good HeNe if you don't need to.

Way to go GG, I hope you figure these out! Let me know if I can help ;D
DH

Dark_Horse said:

Way to go GG, I hope you figure these out! Let me know if I can help ;D
DH

Click to expand...

From Sam's laser FAQ:

http://www.repairfaq.org/sam/laserhen.htm#hentoo

(About 55% down the page)
Getting Other Lasing Wavelengths from Internal Mirror HeNe Laser Tubes

Peace,
dave

This concept intrigued me. I was unable to duplicate your "rainbow" effect. However, after reading the above section in Sam's Laser FAQ's, my curiosity got the better of me. I decided to sacrifice one of my greens to the gods of knowledge.

The tube is significantly longer (14" as opposed to 8") and it is using more power (20KV as opposed to 12KV). However, here's what it looks like inside:





Inside it's the familiar orange/red, but coming out of the end is green. So it is a combination of power and filtering that separates the color lines.

The black, plastic "cap", with the aperture is still connected by "something." I cannot see what it is and I cannot get it loose enough to see if I can disconnect it. I MAY try to get it off again later, but right now, it is going to make one hell of a display.

Peace,
dave

I actually just tried the experiment in sams faq with just a simple front surface mirror on the OC end, and a diffraction grating after the HR mirror, of my ~1.5mW tube. I was able to get some 'flicker' of different lines. No drastically different colors such as yellow or green, but there was a tiny spot that would flicker in and out as I got the alignment perfect on the mirror (remember, I'm just holding this thing with my fingers ;D). I'm thinking maybe it was the 629.4 or 635.2 line, but the color was so similar, and the output so miniscule since it was coming out of the HR end, that I couldn't really tell. Pretty neat either way. Its weird to see the spots start to 'flicker' as you get it perfectly in line with the tube.

I'm really interested in this. Now that I've gotten my diode collection complete, I need to start working on gas lasers now, HeNe sounds like a good place to start.

wow! that is some neat shizz!