View Full Version : Full Spectrum 5th Gen Hobby Laser's naked CO2 glass tube: purple "plasma" dangers?

angie brennan
03-23-2013, 2:11 PM
Hey everybody, this is my first post ever!

And now a little disclaimer: I'm not asking for safety advice so much as looking for pointers to literature which might help answer my question below!

We have a 5th Gen hobby laser from Full Spectrum, and the most curious part of the design is that the glass laser tube is fully in view through the acrylic window, in the lasering chamber, and not in its own hidden compartment. When the laser is firing, the tube itself lights up purple-lish (plasma). I am concerned because I have never seen a laser with its tube in full view during normal operation. Again, keep in mind it is still behind the acrylic window on top, but totally visible through the window.

Does anybody have any information on this light emitted throughout the length of the tube itself, and whether we might be exposing ourselves to radiation other than the usual evils of CO2, which might be escaping through the acrylic window? For example, maybe ultraviolet? Just to be clear, I am not talking about the laser light leaving the normal aperture, I'm talking about looking at the tube itself, which glows during operation. Just the fact that it's glowing into the visible spectrum got me thinking that maybe there's so other junk in there too!

I always use properly rated CO2 laser glasses as an extra precaution, but if the tube itself is emitting other evil wavelengths...

Anyway, I am considering covering the glass tube with a spiral winding of black electrical tape, or even some wide diameter black heat-shrink tubing.

I tried Google all morning with no luck. There is lots of literature on protecting your eyes from the usual suspects (infrared), but I couldn't find any literature describing what possibly harmful wavelengths, if any, might be emitted from the rest of the tube along with the visible plasma.

Any pointers/thoughts would be very much appreciated! And with that, I finish my first post ever here the Creek!

PS the tube is one of these typical Chinese-made glass tubes

Rodne Gold
03-23-2013, 3:27 PM
I don't think it's an issue , the glass and the acrylic window should screen stuff out if there is some radiation , If it bothers you or if you think there might be some danger , stick a piece of cardboard on the window...

Richard Rumancik
03-23-2013, 9:08 PM
Hi Angie - I can't give you specific links but maybe look at info related to building your own glass-tube co2 laser. (There are Youtube videos showing people running glass-tube lasers on the bench but this is not conclusive.) I personally doubt that you will be exposed to anything from the side but you are correct to err on the side of caution. However I would not put tape or heat shink on the tube as it may affect heat transfer. A shield as Rodne suggests is safer.

angie brennan
03-24-2013, 2:28 PM
Thanks for the info guys.

Part of me is surprised that I'm the only one concerned about the naked tube, and the other part of me finds comfort in this. Yes, I've seen those YouTube videos too, but it doesn't necessarily convince me that people on youtube are doing the right thing. In fact, I've seen Full Spectrum (the manufacturer) run the laser with the window completely open in their un-boxing tutorial... I guess they aren't as afraid as I am, but to their credit, they themselves did say "don't do this".

Maybe I can find a physics student at the university who can measure it for me. I don't really want to block the main window because then I can't supervise my jobs for flare-ups, etc.

Anyway, thanks again for your thoughts. If anybody else has comments, I'm all ears!

Richard Rumancik
03-24-2013, 10:49 PM
I didn't mean that you should block the main window such that you can't see the workpiece. I don't know this machine - but what I suggested is that if you want to shield it from view, do so without "insulating" the glass tube. Maybe a shield 1" away from the glass?

One of the reasons for not running these in the open is because of the high voltage present.

Rodne Gold
03-25-2013, 2:40 AM
Yeh , I thought there was like a sub window behind which the tube operated..kinda cool star wars effect...
But if the tube is open , especially at the HT end , that IMO is a LOT more dangerous than the glowing plasma display (As richard so rightly says)
Any accident within the machine or something hitting the tube by mistake could have *shocking* consequences...
Enclose the tube whichever way possible...

angie brennan
03-26-2013, 3:22 PM
Hi Rodne, thanks for pointing that out, I didn't even think about the high-voltage terminals being exposed. I just checked, and thankfully, they are well-protected from my little fingers and even the metalwork with a thick insulating tube and putty. Also, the unit does have an interlock when you lift the top window, the CO2 laser shuts off... though we all know somebody who has had these locks "malfunction" (either accidentally or intentionally ;)).

I guess in the end I will use my CO2 safety goggles and be happy. Nobody has even mentioned that the flares generated by the burning material might present harmful wavelengths, just like welding. I'm not going to take any chances... I now have safety glasses that are rated with Optical Density (aka OD) greater than 7+ at 200-360nm (covering UVA +UVB) as well as and CO2's 10600nm wavelengths, so I hopefully I'm covered.

Perhaps I am paranoid, but with my eyes, I'd rather be extra safe than sorry!

Rodne Gold
03-26-2013, 4:59 PM
The lid acts as safety glasses , or it should. I have never heard of anyone getting anything like arc eyes looking at the laser work (thru the lid that is)