I used to work with Nd:YAG lasers so I have some familiarity but this is not my area of expertise.
All protection like all security is a balance of different things.
Some of you fucking people really kill me when I talk about gun safes. Just because you spent a lifetime of thinking how you are going to Oceans 11 your way into a safe doesn’t mean some meth-head ransacking your house is going to put in that level of work and nothing short of a $10,000 AmSecTL-30 makes you happy, but since none of you actually drop $10,000 on that TL-30, reading the comments does little more than give me heartburn.
*** Rant Over ***
So…
I’ve been looking at laser safety glasses.
I am deliberately leaving out Chineseium garbage.
Here are my balance points.
Wavelength – blue and green lasers seem to be the most popular so 445-532 nm. I know a lot of green lasers also kick out near IR in the 808 – 1064 wavelengths from the KTP doubler.
Optical Density – more is better, these people are trying to blind you with a laser
Visible Light Transmittance – more is better so you can see to defend yourself. Unfortunately, VLT and DO are generally counter to each other, more OD less VLT.
Impact Protection – they are using lasers but also fireworks, glass bottles, and other eye-damaging objects. Protecting your eyes from lasers but not shrapnel doesn’t help you.
Price – if you can’t afford them, what’s the point? Yeah, I know “no price too high for safety” so then why are you not walking around in Hesco SAPI plates? Let’s be reasonable here, we all have budgets.
Scenario:
Let say or enemy is packing green and blue lasers in the 1000 to 5000 mW range. That seems to be the peak for handheld laser pointers online in the $100 price range.
You are caught in a protest because they blocked the road and are shining lasers in your face through the windshield. You need enough protection to GTFO without losing your vision.
I’ve narrowed down my selection and I am looking for advice.
Revision Military Stingerhawk GF-8. The GF-8 are the only ones I’ve seen available for civilian sales.
OD 2.5 for green, OD2 for NIR. 50% VLT
Z87+ and military ballistic impact rating.
$200.
Philips Safety Laser Strike.
OD 2 for Blue 445-450nm, OD 2.5 for green 532nm, No NIR. 43.0% VLT.
No impact rating.
$150
Philips Safety KTP.
OD 6 for 190-532nm blue and green. No NIR. 46% VLT
Z87+
$100
Philips Safety Diode YAG Harmonics.
OD5 190-534nm, OD5 830-1090nm, OD7 1064nm, VLT 28%.
Z87+
$265
Here is my question for the laser experts:
From what I’ve seen, most pilots laser safety glasses don’t block NIR, and blocking NIR, blue, and green cuts the VLT to very low (below 30% which is a dark pair of sunglasses).
I’m leaning in the direction of the KTP. They have the best price at only $100, have a decent light transmission at 46%, and a very high OD for blue and green but don’t block NIR.
The YAG harmonics have the best laser blocking but a 28% transmission are probably too dark to use at night limiting their usefulness, and $265 is pretty steep.
The Revision are tactical eyewear and will protect your eyes from a lot of abuse but the OD is the weakest, although it does block the NIR with 50% VLT, it doesn’t block blue, only green. $200 is rough but doable.
How important is NIR protection vs OD for the green light in a diode laser? Is it worth sacrificing the NIR for high OD on the green with a VLT that isn’t too dark?
What is your advice?
Disclaimer: I am a laser user and have specified laser protective eyewear. Most of my experience is with Q-switched and modelocked Nd:YAG, Nd:Glass and Ti:Sapphire lasers, frequency tripled or quadrupled. This is not medical or laser safety advice, et cetera.
Typical conversion efficiencies from the doubling process are 10 – 50%, depending on a bunch of factors. So if the laser is putting out 1 W of 532 nm light (green), it will likely be starting with at least 2-3 W of 1064 nm (near-infrared).
A good laser vendor will include something called a dichroic, which will reflect the starting wavelength into a dump, while allowing the frequency-upconverted light to pass. Good dichroics can be expensive, likewise good band-pass filters, so it would not surprise me at all if these lasers are letting at least as much NIR through as they are visible.
Re why pilot safety glasses don’t include NIR, I can think of a few possible reasons. The long-wavelength light will definitely diffract faster than the visible, so for instance it’s possible that at the expected ranges, the expected IR spot size is so large the power density isn’t a concern. There are other possibilities as well; but bottom line, the divergence wouldn’t make that much of a difference at typical pistol ranges. I would still be concerned about it.
Honestly, after reading the last post and thinking about it a bit, I’m leaning towards ThorLabs LG10C:
190 to 534 nm, OD = 7+
850 to 925 nm, OD = 5+
>925 to 1070 nm, OD = 6+
960 to 1064 nm, OD = 7+
35% VLT
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=762&pn=LG10#2530
Note that it’s not really emphasized in the page, but these are also Z87.1-2003 rated, so they also provide impact protection.
Price is around $215.
Most of the other laser and optics companies out there will have something similar. Again, I would not buy this sort of thing from Amazon. At least, on the bright side (pardon the pun) the power ratings of the lasers being bought are also likely on, how shall I put this, the “optimistic” side.
Re the disclaimer: to be absolutely clear, I’m a laser user, and have received general laser safety training and training specific to the hazards of the lasers I use, which do not include what Antifa and their ilk are buying. (Probably. If I see someone with a backpack and a long extension cord, I am prepared to believe otherwise.) I am not a laser safety professional.
And are they citing input power or output power?
The laser manufacturer should be specifying the laser average output power (and/or pulse energy and rep rate if a pulsed laser) and wavelength. And also laser class, e.g. Class I is always eye-safe. There is a standard(ish) format label that should be affixed near the output window, something like this:
https://www.usacarry.com/wp-content/uploads/2013/07/laser-warning-labels.jpg
Three other thoughts.
One, if the glasses work as they should, it might not be obvious to you that you’re being lased. You will need to pay attention to things like, oh, small metal tubes being pointed in your direction. (Of course, this is a danger sign anyway.)
Two, if you buy a pair of laser safety glasses … don’t just leave them on the dash of your car or toss them loose into the glove box. Treat them carefully. No abrasive cleaners, no solvents, etc. I’ve no idea of the thermal stability of the dyes etc. used as part of the lens formulation; I do know that scratches and dings will degrade the protection to a degree, both optical and impact, and are to be avoided if possible.
Three, if someone is working with a really powerful laser, say multiple watts, it can melt through if held in the same spot long enough. The lenses are plastic, which doesn’t have great thermal conductivity, and they work by absorbing the laser light. So a high enough power, on the same spot, long enough, will melt and / or burn the lens. So if you think you’re being lased, don’t just stand there and laugh at them. Get out of there.
If you can’t justify spending $100 -$200 for Laser safety glasses, here is a suggestion. Hold up a mirror which will reflect the laser beam and direct it towards the closest “peaceful demonstrator”. Chances are that he doesn’t have a pair of laser safety glasses on!
I don’t think that would violate any laws.
I’m more of the thought that I have a few grand laying around for a rifle, but maybe I should be looking into a nice big juicy laser with a splitter. After all, what’s good for the goose…and all that…
KTP is suboptimal against nearby yahoos with cheap (unfiltered) green lasers, but looks like the right thing for use around, e.g., engravers with blue laser heads installed. Could be one of the frame styles on offer even works over normal-sized glasses?
And, hey: they’ll sell you the Near VIS filter plastic in sheet form! Just what I was looking for to make a safety cover (mostly opaque, with a moderate-sized window) for the router/engraver, and the price isn’t horrible.
For those with overly bulky glasses, or for general riot wear, I see there’s also the “Laser Safety Face Shield for Argon and KTP” – amazingly only $199, but it still doesn’t block the NIR.
What about mirrored sunglasses? Might not block much but it’s more of a “if I go down you go down!” 😀
Thank you very much for the article and comments.
Having no experience in this area I’d be flailing in the dark without your inputs and I’m rather fond of my eyes.
https://www.logsa.army.mil/psmag/archives/PS2008/663/663-49-57.pdf
What about the ones listed here that protect against 2w and 3w lasers? Anyone have any further info on those?
What a scrub, he doesn’t even buy a TXTL x6 rated safe. It’s like securing his valuables isn’t important to him or something.
Ok, trolling over.
I think what happens is you offer an anecdotal quip and because of its brevity, people trying to be helpful push it from passing comment to doctoral dissertation defense trying to provide more information and be more helpful.
It’s my understanding that the IR is mainly an issue because it doesn’t trigger your blink reflex, so it could conceivably be in your eye longer before you became aware of it. If the IR is always accompanied by the green, you should be very aware of it, moving your head or closing your eyes.
So if I remember that right, the lack of IR blocking is less of a concern. Until they start using just IR lasers…
n
This is exactly what I was looking for too. I need to be ready for these yahoos.
I know IR can be blocked by glass, is that the same thing with NIR? So potentially in a car you would be fine at least on that?
Hopefully we can narrow down the best. I want to buy a pair for sure.
This site has a lot of info, and seems to downplay the threat. I’m skeptical but here it is:
https://www.laserpointersafety.com/protests/index.html