FYI: On the OMTech AF2028 and MF2028 chassis direct line of sight of the laser can be achieved while the machine is fully closed.
First, there can be direct line of sight of the laser through a gap on the rear of the top door when standing to the side of the machine. Second, there can be direct line of sight of the laser through a gap in the front panels while standing in front of the machine. The second gap is at about eye level for small kids.
Not to mention the attractive view through those passthrough hatches:
On my machine, the gap at the rear of the lid is behind the beam line, so there’s no direct path outward. That’s also true of the edges, because they’re beyond the boundaries where the laser head stops.
A strip of EVA foam along the front lip would seal reasonably well against the top of the passthrough hatch.
My Shop Assistant has long since grown up, moved out, and started accumulating their own shop, so I’m not worried about little ones underfoot. However, when the neighbor’s kids can see over the edge of a workbench, that’ll change: I’m gonna show 'em how to get into so much trouble. 
There is no direct eye contact with the laser, it may be reflections, but not direct laser beam from the tube or mirrors, that is technically not possible.
But of course you have to be aware of safety, always.
Quick question, who has never run their laser with the lid open, or adjusted their optics with the lid closed?
I did some research trying to understand “but exactly how safe/unsafe is it?”.
You can potentially damage your cornea (lens of your eye) and retina (part of eye that detects the light). CO2 lasers are used in laser eye surgery, suggesting your cornea will absorb and protect your retina from CO2 laser light. Injury to your cornea will be from cutting it or getting a cataract. Cutting your retina requires pointing the laser beam directly at your eye (viewing the laser dot on the part being cut is not enough). This would occur via a unexpected laser reflection from the part being cut. I don’t know how likely this is. To get a cataract you need to heat your cornea to some combination of temperature and time. Is directly viewing the laser dot or a unexpected laser reflection enough energy/time to heat your cornea? The numbers for this probably exist but I haven’t tried calculating it.
Damage to your retina could theoretically occur by viewing the visible-spectrum light emitted during cutting at the laser dot. I don’t have numbers/calculations for how long you would need to look to cause damage.
I’ve seen internet stories of people operating CO2 lasers without any safety barriers and they didn’t immediately go blind…
I run my OMTech China Blue with the door open at least an inch to allow intake air flow. I’ve run it with no panels at all and quite frequently in this configuration.
I believe most people think of a focused laser as a tiny, high energy emf reflecting as a tiny emf field.
Simple fact is what makes a laser useful, is the lens, it takes a relatively low power emf field and focuses it to a tiny spot, putting all that energy into a very small area. Even more simply, after passing through a lens, after the convergence point, the beam diverges greatly and quickly looses power. Anyone that’s used a machine out of focus knows how critical focus is.
If you are 3 feet away, it would be like focusing 3 feet past the focal point, meaning all of that energy is dispersed over a much large area. You don’t get a focused spot or beam when it’s reflected, you get the same divergence over distance that you get on the machines lens.
The most safe operation occurs if you understand how the machine works. Chances of reflections out of my China Blue could only occur is if one of the mirrors fell out at the exact angle to reflect it out of the machine. This isn’t the machines fault or a safety issue directly.
Another point, is that hundreds of thousands, if not millions of these machines are out there operated by people with an IQ of less than a bag of rocks, how many of these have been blinded or damaged vision? I’ve never read about anything that makes sense like this occurring. There’s probably more led lasers out there with the low cost safety goggles supplied with the machine. These must work or we’d heard about people with seeing difficulties.
I use the supplied safety glasses on my fiber as it’s all open. However when I find videos of people using 1.5kW or larger fiber rust remover without any kind of safety glasses, I wonder how much truth this safety protection holds true. This is especially true when I can’t lase baloney, bread or hot dogs.
Understand how they work and use common sense around them. I wear safety glasses doing most work, stuff ends up hitting the glasses, so I’m an advocate of safety glasses.
This is not a recommendation to look from m3 back to m2 and the tube with your remaining eye.
Yes, it is possible, definitely.
Here I am not sure what wavelength the ophthalmologists use with their laser, I have had surgery myself but I did not dare to ask in this situation…
However, Reflections from our lasers, no matter which type, that hit your eye is dangerous enough to cause damage.
You can do a simple test, grab some meat from the Christmas duck (or turkey) and place it under the laser. Shoot at the meat and see the result. Then you try with a pair of protective glasses, which are placed in the beam, but before the duck. After that you can try with a pair of old reading glasses (glass, not plastic), here the result between CO2 and diode laser is impressive. Unfortunately I do not have (yet) a fiber laser… but I wonder if the damage here is just as bad.
I have always focused on safety, but must admit that over time I have lowered the level a bit, but I hope I do not become like the Chinese we see selling/demonstrating 2000W laser cleaners, without shoes and glasses.
I don’t know how many users there are here in the LB forum, but wouldn’t we have heard about it if there had been a serious accident?
May the gods forbid it, - therefore, use your brains when working with tools.
PS. if you ask around here if anyone has burned their fingers in a laser…I definitely know someone.
