Can I look at the laser while it engraves?


#1

Teacher w/ new glowforge today… The kids want to stare at it cutting, but I don’t have any idea if we can look at it while it cuts. We don’t have any special glasses. The lid is closed.


#2

Yes


#3

Thanks! Are there any warnings about staring at it for 5+ minutes? They cant look away…


#4

If it is a Basic, then you can stare at it as long as it’s comfortable for you, but there are certain things that when you cut or etch them will throw a very bright light that I wouldn’t stare at for long. It will cause a temporary blind spot in your vision, and it’s probably not a good idea to do it too much.


#5

All the light coming through the glass is harmless, it could leave an after image but harmless.


#6

Cool. Thanks so much. Yeah, when it does a full cut I figured it was probably a “look away moment”… What about the plasma container? Same? Totally fine to look at? I don’t wanna send home half blind kiddos… Haha… Thanks for your time. I’ve been chasing them away yelling “just glance! just glance! we don’t know if we can look at it yet!” haha… It’s been the new game for the day for them.


#7

Plasma is totally fine to watch…I like to keep my tube clean for that reason. Very Frankenstein! :smile:


#8

Right? So awesome… Is the liquid in there nitrogen? It looks like it’s vaporizing into a gas as the plasma charges.


#9

No idea! (I just find myself chuckling with an evil laugh when it fires up.) :smile:


#10

rofl


#11

I have gotten involved watching to see if can lower cut thru numbers, and of course I got a temporary blind spot for my efforts. Harmless but not something you want to do all the time.


#12

CO2 lasers actually have a mix of gasses. Helium is usually the primary constituent. Then there’s CO2 of course, and a similar amount of Nitrogen and maybe a little bit of Hydrogen or Xenon. It’s a CO2 laser because that’s the gas that emits the light that drives the laser, even though the gas in the tube is probably only about 20% CO2. The laser’s output is in the low infrared, though. You can’t see that light at all (which is one of the reasons it’s so dangerous. You can’t see it so you don’t know to look away. But the energy is still there cooking your retina).

The good news is, the light you see radiating down the middle of the tube is basically what you see when you look at a neon light, for pretty much the same reason, and is no more a danger (to your eyes) than the signs in your local Pub.


#13

Nice! Thank you for the very thorough answer… I’ll make sure to explain this to my students tomorrow.

Thank you!


#14

So, with fiber optics in networking (I’m the director of academic tech), we have a laser that’s not visible because it’s so low on the infrared spectrum for our sfp’s and gbic cards. You aren’t supposed to look at it for the same reason… It can do pinpoint damage to your eyes w/o you even knowing it… That said, if you take a cell phone and point it at the end while plugged into a live sfp card, you can actually see it blinking because cameras pick up infrared. Would you expect you could see a bunch of visible light via your cell camera on the laser cutter in the same way?


#15

I’m guessing yes. Most CMOS sensors have an IR blocking filter because otherwise the sensor would be overwhelmed by the IR. Because it’s more sensitive to lower frequency light. But a filter doesn’t have infinite attenuation so some IR will still get through. If it’s strong enough to appear “brighter” to the sensor than the visible light you could definitely see something.

This trick ought to work with your TV remote, too. That’s also IR.

But you won’t necessarily see a beam. There has to be something to reflect and scatter the beam in order for the beam to be visible to the camera (or eye). Just like you can see the beam from your laser pointer in fog better than clear air. Most lasers are invisible in clear air regardless of the frequency of the light. I think the only exception is green. For reasons I don’t remember and am not too sure I am even remembering correctly, the atmosphere will reflect and scatter green.


#16

I have had the same question on my mind for a little while, glad someone asked (and that I was looking through this section).

Also, I dig the yajirobe profile pic. Have been a fan of the series for my whole life!


#17

Probably not because CO2 laser light is far IR which has a wavelength more than 10 times longer than laser diodes and IR leds, which are near IR, just below visible red.

Near IR will pass through glass so it can get into an optical camera. Far IR is completely absorbed by glass. Its photons have 10 times less energy, so even if you replaced your camera lens with a laser lens it probably won’t trigger the sensor.

You might be able to see it with a thermal camera.


#18

Haha… Thanks! I drew it years ago off a really low resolution version.


#19

Yeah, I was engraving some subway tiles this past weekend, and I had to look away. It was quite bright!


#20

Helium, huh?

So, is the primary lifespan issue with CO2 lasers that the helium gradually escapes the glass envelope?