# Will mirrored sunglasses protect your eyes from damage by a powerful laser beam? **URL:** \ **Category:** Factual Questions\ **Created:** [November 8, 2005, 8:54pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103 "2005-11-08T20:54:25Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [November 8, 2005, 8:54pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/1 "2005-11-08T20:54:25Z")
…like the one generated by this portable military laser? [US military sets laser PHASRs to stun](http://www.newscientist.com/article.ns?id=dn8275) > [@](#): > > The US government has unveiled a “non-lethal” laser rifle designed to dazzle enemy personnel without causing them permanent harm. But the device will require close scrutiny to ensure compliance with a United Nations protocol on blinding laser weapons. > > The Personnel Halting and Stimulation Response (PHASR) rifle was developed at the Air Force Research Laboratory in New Mexico, US, and two prototypes have been delivered to military bases in Texas and Virginia for further testing. > > The US Department of Defense (DoD) believes the weapon could be used, for example, to temporarily blind suspects who drive through a roadblock. However, the DoD has yet to reveal details of how the laser works and has yet to respond to New Scientist’s requests for further information. ---
**Author:** ![eviladam\_part\_2](https://avatars.discourse-cdn.com/v4/letter/e/da6949/32.png) [@eviladam\_part\_2](https://boards.straightdope.com/u/eviladam_part_2)\ **Post date:** [November 8, 2005, 9:06pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/2 "2005-11-08T21:06:48Z")
as long as they don’t let any light through, yes. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [November 8, 2005, 9:10pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/3 "2005-11-08T21:10:45Z")
> [@eviladam](#): > > as long as they don’t let any light through, yes. Then it would be called a “blindfold”. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 8, 2005, 9:12pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/4 "2005-11-08T21:12:49Z")
> [@eviladam](#): > > as long as they don’t let any light through, yes. In which case, they would be useless as eyewear, now wouldn’t they? The answer is, it depends. It depends on the strength of the incident beam, the amount of dilation of your pupils at the time of exposure, the wavelength of the laser radiation and the attentuation of light at that wavelength by the glasses. I doubt if ordinary off-the-shelf mirrored sunglasses will be sufficient to fully protect you, though they may provide some minimal level of protection against the worst of the effects. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [November 8, 2005, 9:14pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/5 "2005-11-08T21:14:40Z")
I certainly wouldn’t let anyone test that on me. ---
**Author:** ![h.sapiens](https://avatars.discourse-cdn.com/v4/letter/h/e0b2c6/32.png) [@h.sapiens](https://boards.straightdope.com/u/h.sapiens)\ **Post date:** [November 8, 2005, 9:16pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/6 "2005-11-08T21:16:21Z")
I’ve never seen a more appropriate place for the following: “The goggles, they do nothing!” ---
**Author:** ![UncleRojelio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unclerojelio/32/3160_2.png) [@UncleRojelio](https://boards.straightdope.com/u/UncleRojelio)\ **Post date:** [November 8, 2005, 9:18pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/7 "2005-11-08T21:18:46Z")
> [@h.sapiens](#): > > I’ve never seen a more appropriate place for the following: > > “The goggles, they do nothing!” I see you finally lost your accent. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [November 8, 2005, 9:23pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/8 "2005-11-08T21:23:51Z")
They certainly wouldn’t do any good against an industrial-strength cutting laser. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [November 8, 2005, 9:27pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/9 "2005-11-08T21:27:31Z")
> [@ultrafilter](#): > > They certainly wouldn’t do any good against an industrial-strength cutting laser. So the notion that a mirrored surface (ie the glasses) would efficiently reflect a laser beam is overblown? ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [November 8, 2005, 9:28pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/10 "2005-11-08T21:28:46Z")
> [@astro](#): > > So the notion that a mirrored surface (ie the glasses) would efficiently reflect a laser beam is overblown? I’m not sure I’d want to be where the laser beam was being reflected to, either. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 8, 2005, 9:31pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/11 "2005-11-08T21:31:21Z")
> [@astro](#): > > So the notion that a mirrored surface (ie the glasses) would efficiently reflect a laser beam is overblown? Yes. The reason you can _see_ through them is, obviously, because they let SOME percentage of the light through. Typical mirrored sunglasses reflect about 80-85% of the incident light; the rest is either transmitted or absorbed by the lenses. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [November 8, 2005, 9:34pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/12 "2005-11-08T21:34:22Z")
> [@astro](#): > > So the notion that a mirrored surface (ie the glasses) would efficiently reflect a laser beam is overblown? Even mirrored sunglasses let _some_ light through, or you couldn’t see through them. If the light they let through happens to be the wavelength of the laser beam, it would be just like looking at the beam. A lot of lasers don’t operate in the visible range of the spectrum, the only way you can see them is with something like smoke in the air. If they are not visible, then a mirrored surface that reflects some visible light might not be a very good protection. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 8, 2005, 9:35pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/13 "2005-11-08T21:35:01Z")
It’s not whether the glasses are mirrored, it’s what fraction of the impinging light gets through. With sunglasses that’s typically between 1 and 10%. For a laser, that’s nothing. It would stuill hurt you. They do manufacture laser goggles for laboratory safety, and these typically have optical densities of 4 or higher. (For comparison, 10% transmission is OD 1, 1% is OD2, so normally glasses are between 1 and 2. OD4 is 0.01% transmission). This is achieved by the use of absorbing dyes, thin film coatings, or holograms, and sometimes by all three (especially if you need protection at multiple wavelengths). Edmunds sells lab goggles of this type for protection from common lasers. The more optical density you require, and the more wavelengths you need protection from, the higher the cost. Of course, you can protect yourself from all wavelengths by wearing a brick on your face, but then you couldn’t see at all. The trick is being protected yet having some vision. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [November 8, 2005, 9:41pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/14 "2005-11-08T21:41:33Z")
> [@Duke of Rat](#): > > A lot of lasers don’t operate in the visible range of the spectrum, the only way you can see them is with something like smoke in the air. Not unless this putative “smoke” is fluorescing in the visible spectrum. Ordinary smoke or fog might scatter the light making a visible-spectrum laser beam more easily visible, but an IR or UV beam will still be invisible. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [November 8, 2005, 9:43pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/15 "2005-11-08T21:43:56Z")
> [@CalMeacham](#): > > It’s not whether the glasses are mirrored, it’s what fraction of the impinging light gets through. With sunglasses that’s typically between 1 and 10%. For a laser, that’s nothing. It would stuill hurt you. > They do manufacture laser goggles for laboratory safety, and these typically have optical densities of 4 or higher. (For comparison, 10% transmission is OD 1, 1% is OD2, so normally glasses are between 1 and 2. OD4 is 0.01% transmission). This is achieved by the use of absorbing dyes, thin film coatings, or holograms, and sometimes by all three (especially if you need protection at multiple wavelengths). Edmunds sells lab goggles of this type for protection from common lasers. The more optical density you require, and the more wavelengths you need protection from, the higher the cost. > > Of course, you can protect yourself from all wavelengths by wearing a brick on your face, but then you couldn’t see at all. The trick is being protected yet having some vision. I wonder if night vision goggles would protect you. ---
**Author:** ![Valgard](https://avatars.discourse-cdn.com/v4/letter/v/7feea3/32.png) [@Valgard](https://boards.straightdope.com/u/Valgard)\ **Post date:** [November 8, 2005, 9:46pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/16 "2005-11-08T21:46:55Z")
> [@Duke of Rat](#): > > A lot of lasers don’t operate in the visible range of the spectrum, the only way you can see them is with something like smoke in the air. Minor nitpick - As long as the beam of light is in the visible spectrum then you’ll be able to see it when it scatters off anything, whether it’s the wall or smoke in the air. That’s why you can see your headlight beams in the fog, flashlight beams in the campfire smoke or a laser beam in mist at the groovy Laser Show. If the light is not in the visible spectrum then you won’t be able to see it no matter what is in the air (unless you shine it on something that flouresces under that wavelength, I suppose). An IR or UV laser beam is pretty much invisible…for example you don’t see beams of light coming out of your TV remote control, even if someone is smoking up a storm in your den. ---
**Author:** ![Casey1505](https://avatars.discourse-cdn.com/v4/letter/c/dc4da7/32.png) [@Casey1505](https://boards.straightdope.com/u/Casey1505)\ **Post date:** [November 8, 2005, 9:47pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/17 "2005-11-08T21:47:56Z")
Don’t night vision goggles amplify light, making them useful in near dark conditions? Wearing them to look at a candle, for example, I thought, would probably blind you, at least temporarily. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [November 8, 2005, 10:22pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/18 "2005-11-08T22:22:58Z")
Can you set the PHASR on stun AND kill? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 8, 2005, 11:08pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/19 "2005-11-08T23:08:06Z")
> [@](#): > > Don’t night vision goggles amplify light, making them useful in near dark conditions? Wearing them to look at a candle, for example, I thought, would probably blind you, at least temporarily. That depends on the night vision goggles. The simplest sort of night vision goggles is just a pair of binoculars with really big primaries. These would assuredly make the damage worse. There may be some which electronically amplify the light indiscriminately, and these could also make the damage worse. But I think (and feel free to correct me on this) most of them nowadays consist of a digital camera and display for each eye. In this case, it would be trivially easy to build in safeguards such that the display can’t get so bright as to blind the wearer. So this sort would offer complete protection against a blinding weapon. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [November 8, 2005, 11:13pm UTC](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103/20 "2005-11-08T23:13:56Z")
> [@Chronos](#): > > That depends on the night vision goggles. The simplest sort of night vision goggles is just a pair of binoculars with really big primaries. I’ve never seen a passive optical device referred to as “night vision” - have you? > [@](#): > > But I think (and feel free to correct me on this) most of them nowadays consist of a digital camera and display for each eye. I t hought they still used microchannel plates to “amplify” light - there are no digital signals involved. A photocathod converts light into electrons, and the electrons are accelerated and amplified by a strong electrical field before hitting a phosphor screen. But I think you are correct in that its output brightness is limited, and cannot damage your eyes. [Next page](https://boards.straightdope.com/t/will-mirrored-sunglasses-protect-your-eyes-from-damage-by-a-powerful-laser-beam/330103.md?page=2)