Dangerous Area of a Hair Removal Laser

[dedesperado]

From what distance does the diffuse radiation of a „hair removal laser“ cease to be a threat?

I apologize for the peculiar question, but I'm curious about the following matter: I walked past the window of a hair removal studio about 50 meters away earlier, and I noticed repeated bright red flashes inside, likely indicating laser work. Therefore, I looked in the direction of the window. Now the question is: Is the radiation from a laser in this case (behind a glass pane + 50 meters away) still harmful to the eye? Personal interest and a little concern drive me to this unusual question. Thanks for the answers!

 

[Vanadium 50]

This sounds like a mix of medical and legal advice, neither of which we can provide.

It's also hard to gauge what a "red flash" means after one or more reflections, transmissions through glass, and the divergence with distance.

 

[DaveC426913]

A couple of things:

1. Just because you see a flash doesn't mean the laser was pointed directly into your eye. There's no real risk unless it's pointed right into your eye, which is relatively unlikely.
2. Even at that, any anticipated damage will be proportional to duration of exposure on that specific site on your retina. If you glanced instinctively but then looked elsewhere - as opposed to staring at it - you should be just fine. The risk comes from it "burning-in". That doesn't easily happen inadvertantly.

But if you have any concerns, you should visit your eye doctor.

 

[berkeman]

Welcome to PF.

From what distance does the diffuse radiation of a „hair removal laser“ cease to be a threat?

I apologize for the peculiar question, but I'm curious about the following matter: I walked past the window of a hair removal studio about 50 meters away earlier, and I noticed repeated bright red flashes inside, likely indicating laser work. Therefore, I looked in the direction of the window. Now the question is: Is the radiation from a laser in this case (behind a glass pane + 50 meters away) still harmful to the eye? Personal interest and a little concern drive me to this unusual question. Thanks for the answers!

Your profile says that you are from Germany, so your industrial/medical safety regulations are similar to those here in the US.

Those safety regulations limit the amount of radiation that can be "leaked" out of medical facilities. Think about when you visit the dentist -- when they take x-rays, they are in rooms equipped with shielding in the walls, and the dental folks are careful about how they aim the x-ray probe/generator before they active it.

For lasers used in medical/industrial settings, there are strictly enforced regulations. Hair removal lasers can use ruby red or IR lasers:

https://www.sciencedirect.com/topics/medicine-and-dentistry/laser-hair-removal

For either one, the inadvertent exposure of folks to those lasers must be limited. If the facility that you were near was following the rules, it is unlikely that you were exposed to any red laser radiation. It would be pretty irresponsible of them (and against the regulations) for them to be treating a patient in front of a transparent window where leaked laser radiation could get outside the building.

https://www.lasersafetyfacts.com/laserclasses.html

Please check your local regulations, and if you still have concerns, visit the facility with a copy of the regulations in your hand and ask to inspect their treatment rooms and look out the windows...

[Thread moved to the Medical forums from the General Discussion forum]

 

[berkeman]

BTW, if the window was just into the lobby of the medical treatment business, you may have just been seeing the reflection of the red laser scanner for barcodes. Those are also regulated, and almost surely were below any regulatory limits when they got to your eyes (like in the grocery store).

 

[JT Smith]

 

[Rive]

Now the question is: Is the radiation from a laser in this case (behind a glass pane + 50 meters away) still harmful to the eye?

No.

What makes laser dangerous is, that it's kind of 'orderly'. That makes handling it (by optics or by eye, for example) very efficient: but in case it's focused the result may be very high energy density in a very small spot (=> may cause harm to the retina).
Once that 'orderly' nature is broken (by illuminated non-reflective or non-transparent surfaces, like: papers, walls, furniture, or like in your case: the skin of the patients) then it's no laser any more, just light.