View Full Version : UV Discharge from Laser

Daniel Wolanski
12-30-2011, 11:49 AM
Hi all,
This is my first post to this forum. I have been lurking for a few weeks and wish I had found this list before buying my laser direct from China. I bought a FAL-F90120S, 2 heads, 100W each from a company called Hubei Future Away Laser Company. They claimed to have shipped many lasers to the US but found out the hard way they didn't have an FDA number to get it past customs. I finally got it through with a LOT of work but learned a lot. Lesson one was not to deal with them again.

The machine appears to be a clone of all the other lasers I've seen mentioned here. Same basic Chinese laser tube (non-RECI), x-y stepper motors, pad entry and LaserCut 5.3 like the Rabbits, etc. I am convinced they buy everything and make there own steel box to put it in. When I asked them a few easy questions like what is the focal length, they just said to put the head a few mm from the material to be cut... yeah right. I found out by trial and error I have a 63.5mm focal lens. I also wanted it 220V but they were clueless on how to build it for US 220 voltage vs. European. They said they were familiar with 120V so I agreed to let them build it 120V. When I got it, it BUZZED terrible when I powered it up. I figured out they put a 220V contactor in it instead of a 120V contactor. Good thing I had a spare 120V contactor laying around.

I got the machine running after a big software learning curve (Lasercut 5.3). Now I am "faced" with a new challenge. I have been running only head #1 so far and not bothered with head /tube #2 yet. I've got about 5-6 hours on the machine and every time I run it, my face gets red.:mad: Actually it's only my cheeks and forehead. I have Co2 Laser safety glasses that I wear all the time and never operate it with the lid open (The magnetic safety switch was broken upon arrival so I had to bypass it). I have been researching different wavelengths of light generated by the laser and went through a scientific approach to try to resolve the problem. Here is what I have done so far..

1)Co2 wavelength 10.6nm is opaque to lexan / plexiglass so it can't be that coming through the viewing portal. So I put UV reflective film from Lowes on the top lexan.... didn't work but left it on.
2) I covered the lexan with cardboard from the outside... didn't work but left it on.
3) I built a barrier between me and the machine from a metal shelf unit. I put 1/8" chipboard as a barrier between me and the machine. I cut a viewing portal in the wood and used .220 arcylic with the UV reflective film on it. The shelf is 6 feet high and the shop ceiling is 10 feet high (maybe the light is bouncing around the room). Didn't work but I left it up.
4) The only part of my body getting red is my cheeks / forehead so I put on a ski mask, made sure I was behind my barrier and ran the machine. It worked. My face did NOT get red!:)
5) Now that I believe the escaping light must be in the UV range, I went through and covered every gap on the machine with black magnetic sheeting. Many of the gaps were at least 1/4" wide and I could see the florescent light I put inside for viewing the cutting with my webcam. I put a black vinyl cover on the lexan viewing portal. I put a top over my "computer cave" to prevent UV bounce back. I put sides on my "computer cave". I removed my face mask and ran the laser for about 20 minutes. My face did not get red.

BTW, I also tried sunscreen and it didn't work. I surmise it must be UVC escaping and not A or B.

My next experiment will be to leave the room completely. I just bought some long USB cables to move the computer to another room. If I get red at all after I move, the wavelength cannot be UV. My hopes is that I am NOT microwaving myself.:eek:

BTW, the red face felt like a windburn more than a sunburn. It would disappear after about 2-3 hours and not lot leave a tan behind.

Today I may try to run laser head / tube #2 only and see what happens. This would tell me if I have a bad bulb on #1.

Has anyone ever come across a mystery like this with their laser?:confused:

Neil Pabia
12-30-2011, 12:02 PM
I have never heard of anything like this happening and I tend to stand over my laser when it is working and watch it. I would not leave the room as that sounds like an accident waiting to happen. I'm sure someone here can give you some good advice on what to do, but so far it doesn't sound very safe to me.

My coworker here has suggested that you put a piece of steak on it and run it for a half hour and see what it does to that. It may give you an idea of what it is doing to you. Sorry, thats how we do things around here...I guess it's a Marine thing.

Rich Harman
12-30-2011, 2:51 PM
I thought you were joking at first.

I run mine with the lid open all the time, watching over it, and I have not experienced anything like what you describe.

Doug Griffith
12-30-2011, 3:04 PM
I run mine with the top open as well. No problems.

Just to be more thorough, what material are you cutting/engraving? It might be possible that you are having a reaction to the fumes that are generated.

David Fairfield
12-30-2011, 3:09 PM
Zoinks! You shouldn't have to run a laser behind a makeshift radiation shield, with a ski mask and goggles on. That's just not right. :eek: I'm with Doug. I'd also want to know if your face ever gets red from just plain excitement or nerves. I remember when my machine was new, I was just about busting with "new toy" excitement, and also nervous that I'd do something dumb and break it.


Emma austin
12-30-2011, 3:18 PM
Wow can't add anything technical, but that really doesn't sound right. I wouldn't go near my machine if it had such obvious visible affects on me!!

Daniel Wolanski
12-30-2011, 5:19 PM
Hi Doug,
I am cutting plain ole Baltic Birch. Nothing exotic or toxic. The vacuum fan works great and sucks out all the smoke. I have it vented outside. I barely smell anything.

I really don't react to many things at all. Having Italian heritage, I tan quite easily and burn very rarely.

matthew knott
12-30-2011, 5:35 PM
Can you see the laser tube, it will be glowing nice and purple! these give off a fair bit of UV , they look a bit like a tanning lamp :) if thats getting out it might be causing the problem, the guy i worked with who set up 2kw lasers always had good face tans and panda eyes were they wore googles!

Doug Griffith
12-30-2011, 5:36 PM
Can you line up another "guinea pig" to stare into the laser with you and see if it affects them as well? Wearing proper glasses of course.

You may want to swap out the protective plastic lid for UV filtering plastic.

Dee Gallo
12-30-2011, 7:01 PM
Can you line up another "guinea pig" to stare into the laser with you and see if it affects them as well? Wearing proper glasses of course.

You may want to swap out the protective plastic lid for UV filtering plastic.

I would rather suggest using a piece of cherry wood as the guinea pig. I commonly will "sun" my cherry wood to help it get a darker color and I know a tanning booth will do it too.

At any rate, this does not sound good to me. Could you run the laser with NO material in it and see if there is a reaction?

Dan Hintz
12-30-2011, 7:18 PM
We're either being punked, you have a rare skin disorder, or (more than likely) this is strictly a psychosomatic reaction. There is no radiation leaving that box except of the electromagnetic kind within the visible spectrum.

Daniel Wolanski
12-30-2011, 7:20 PM
In another test, I turned on the power to the laser but did not fire the laser. I stood in front of the machine to see if the power source for the laser was creating any RF. There was no draw on the power source but I allowed power to get to it by turning on the switch. No red face... therefore it is the laser while being fired and not any of the electronics.

I thought about getting another "test subject" but who's gonna volunteer for that!:cool:

I also thought about buying a cheap UV detector from Amazon. The problem is I think it only picks up UVA /B. The really good ones are $750 and I would rather apply that to a new machine / bulb.

My machine does have the gap in the back under the bulbs that allows a sheet of material to pass through it. I first covered it with the UV film, now I have it covered with black magnetic sheeting.

Attached are 4 pics of my laser and laser cave217718217719217720217721

Daniel Wolanski
12-30-2011, 7:25 PM
I'm very serious and not punking anyone. As far as I know, I don't have any rare skin disorder.

I initially had the computer next to to the machine and just that side of my face got red. I know it's the machine, I just can't figure out what!

Rich Harman
12-30-2011, 7:26 PM
I thought about getting another "test subject" but who's gonna volunteer for that!:cool:

I'll volunteer!

Ralph Y Thorne
12-30-2011, 7:53 PM

This past month I've been cutting a lot of 1/4" Baltic Birch using using air assist on a 80 watt machine. I noticed after only a few minutes my eyes felt like I had been welding without eye protection. This does not happen with other materials...yet.

I have a Jackson full face shield I use when oxyacetylene welding or cutting. I tried it. The problem was gone.

I also noticed the window on your machine is larger than mine.

Rodne Gold
12-30-2011, 8:19 PM
I have also noticed that when cutting at full power and staring at the superbright light without the lid closed , you almost get a sort of welders eyes , not just with my chinese machines but also my normal ones.

Daniel Wolanski
12-30-2011, 8:41 PM
Rich, I may just have to take up your offer since I see that you are only 20 miles away from Monroe.

This problem is frustrating me since I cannot figure it out. Being a mechanical engineer, I like to know how everything works!

Rich Harman
12-30-2011, 9:13 PM
I wouldn't mind at all, kind of interested to see how similar our machines are.

Daniel Wolanski
01-02-2012, 5:06 PM
I did some "research" over the Holiday weekend. I paid my 15 year old son $5 to stand in front of the laser with me for 10 minutes with the door open (safety glasses on). We cut birch but I did not touch it after it was cut. Guess what, no reaction whatsoever. We did this twice! Conclusion" I'm reacting to the burnt wood / glue!!! Now I can take down my nuclear blast barricade!

Send me a PM. I would like still like to meet you and have you come to my shop in Monroe. I am interested in probably getting another machine (maybe 150W) and would like to compare notes on machines and your Shenhui or Rabbit. I am mainly interested in the cutting ability of each.

Kim Vellore
01-03-2012, 12:24 AM
There might be some UV coming out of the tube, since it is a glow discharge type of lamp. You might want to see if there are any thing that can fluoresce like a tubelight. You can try holding a small CFL lamp around the laser to see if it glows or some of the glow in the dark objects can be excited by the UV.