What are the most common mistakes that lead to people damaging their eyes with a laser?

I just getting started with laser engraving, and have just brought my first machine (Ortur LM3).

I’ve got a pretty good understanding of how dangerous lasers can be in general, and of the safety precautions that you should take when using them (My first project is going to involve building a completely blacked out enclosure with a camera rather than a window).

What I don’t really have an understanding of is the kind of “mishaps and accidents” that relate directly to laser engravers that can lead to eye damage.

Could someone go over the most common ones, particularly the ones that beginners are likely to make, so that I can avoid them if I ever use my engraver out of its enclosure (for example, to engrave something big), or try to build protective mechanisms into my setup to make them as unlikely as possible?

For example, can you damage your eyes looking whatever you are cutting for too long, even if you have glasses and are using the tinted acrylic shields that come with most lasers these days?

Is it dangerous to look at the machine when it engraves something that’s particularly reflective, such as polished metal?

Do lots of people accidentally knock their cutters of their benches and end up flipping the beam directly into their faces?

Are the safety glasses that come with the machines likely to be garbage?

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Those are a lot of good questions and I am happy you are asking them.

The overriding answer is that lasers no matter the wavelength should be enclosed. The enclosure should have interlocks that shut down the laser when the laser’s beam has any means of exiting the protective covers. Including falling off a bench :).

I do not trust anything without interlocks. I especially don’t trust myself not to make a mistake.

I don’t use nor recommend the use of laser safety glasses. Others would disagree but my view (pun intended) is that if you need protective glasses you’re in an unsafe condition. Laser glasses are intended for laboratory environments, not hobby environments.

When operating lasers, a mistake will permanently damage your vision. If not blind you will certainly have significant vision loss. This situation is unlike other industrial equipment where you might do repairable damage to your body.

If you are planning to operate a machine of these power levels without interlocked covers in place … that is a bad idea … in all cases. Depending on yourself to not make a mistake is usually when accidents happen.

Forgetting to use glasses, not realizing the laser is armed, and getting unintended reflections, etc are all called “accidents” because something unintended happened. Interlocks dramatically reduce the possibility of unintended events occurring.

Unintended events are especially possible with CO2 lasers because you cannot see the beam. That said, with any high-power laser by the time you see it … well you won’t.

Looking at a laser is only harmful if there is enough power at your eye to damage it. This means that viewing window material must be carefully chosen to block [at the laser’s wavelength] enough of the light energy at the window to prevent overexposure. A blackout enclosure with an internal camera AND interlocks is a good idea.

You will see lasers of all types online with no enclosure and no interlock protection at all. In NO CASE is this safe. That is why they are not certified by any reputable agency.

Note that in CO2 laser applications the laser is not the only lethal danger. The laser power supply is also lethal. Without interlocks, you can easily be electrocuted. If it doesn’t kill you the likely hood of internal damage (fried lungs) is high.

The bottom line; have an enclosure and ensure your enclosure is properly designed to eliminate overexposure and interlock operation.

I spend a lot of time around industrial equipment with interlocks due to moving parts, but I’m not sure how to build one into the LM3, I don’t think that it has an interface for one. Would building an interlock into the PSU be a problem, for example, simply cutting the mains supply?

An Ortur LM3?
I have a laser diode prototype I am playing with.
Was planning to interrupt the 12V to the laser diode drive but have not done it yet.
Do you have any documentation on the laser module or the controller?
A Schematic would be ideal.

Here’s a great website that has a lot of information on laser hazards. There’s even a lot of links to more information.


I got ahold of Ortur support to find out the laser module interface details.
They want to know what machine: Ortur LM3?
They also want to know what laser module is installed?

Absolutely vanilla lm3 10w, still in its shrink wrapping as I’m waiting on the camera for the enclosure to arrive.

I plan to run it off of an SD card as my pc isn’t wireless and is too far to run USB, so any kill switch will need to be physically not software.

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Are there any markings on the laser module

Update from Ortur support:

The tilt is prebuilt in the machine, if you tilt it or shake it it will stop

However, there is a DOOR pin on the back of the motherboard, I am not certain however if the firmware already implements this
If you notice Theresa 6 pin,

I think this [Theresa] was meant to say “there is”.
Note that there is a “DOOR” label on the 6-pin connector.

The support contact is checking with development to see if that pin is implemented in the firmware. I am guessing that if this pin is grounded the controller will pause. If so you would connect this pin to the interlocks wired in series.


I’m worried that this would void the warranty if I used it.

It’s unlikely they would void the warranty for using functions they built into the product.

You could ask Ortur support directly.

The bottom line is the functions you asked for seem to already exist in the product.

Hope that helped.