I read thru numerous posts mentioning the safety glasses to use while operating a diode laser, but for all of the questions I did not see a definite answer.
This week I should receive a new Atomstack A20 PRO and would like to be prepared to use it. What specs. (Pardon the pun) should I be looking for when I buy a pair? Even the color was debated back and forth a bit.
Anyone have any friendly advice for a lowly newb?
Wg
Iāve been shopping for glasses for some time and Iāve studied the subject quite a lot.
The first thing is the wavelength of your laser (for higher energy lasers also for harmonics, but this is not relevant for us), thatās what the glasses need to protect. My laser works around 1080nm, yours, if Iām right 450-460nm (please check this)
So you should look for glasses to block this wavelength.
The other parameter is the blocking efficiency, better quality glasses have this value in Optical Density (OD) and a number like OD4, OD5, OD6, etc. The number shows how many zeros in the percent value they let the given wavelength light thru, like 0.00001%
You can calculate the minimum OD value you need here: Laser Institute of America - Free OD Calculator
There is no sense of just having a general OD value, it must be specified by wavelength, if there is an OD graph, it is the most convincing. The higher is the OD the better (there are glasses up to OD10+, these are quite expensive though).
Another consideration is how much light you want to see at the unprotected wavelength, the more, the better you see. and does not make you take off your glasses every moment, which is a security risk. Thatās why we are looking for selective filtering, so the OD value should be as high as possible at the wavelength of your laser and - if you want more vision - as low as possible at all other wavelengths. if youāre blocking more visible light, cheaper glasses can provide just as good protection. the extreme end of this is glasses with metallic sheets they block OD1000+ for all wavelengths and cheap. 
there is a lot of information here: Home - Phillips Safety
Third, how comfortable the glasses are and how well they protect from the sides, no point if you have a good lens, but the light goes into the corner of your eye from the side, you donāt have to look into the laser to be dangerous. I 3D printed an additional sleeve around my glasses, you canāt try on glasses bought online, and they will never fit your head 100%. if you donāt buy the rubber-edged goggle type.
There may be similarly capable glasses for a good price on ebay, aliexpress, etc. but I couldnāt figure out how to filter out (Pardon the pun) the lenses that were actually tested.
Unfortunately we canāt accurately test glasses at home, there are videos on youtube of ātestingā glasses by letting laser beam thru them, but these āmeasurementsā donāt even come close to the required dynamic range to tell apart a e.g. 0.0001% transmittance from a 0.00001%, and all this would be required depending on the wavelength. When someone burns glasses as ātestingā an OD0 lens will behave exactly the same as a $800 OD10+ you need a laboratory equipped with expensive instruments to make a OD chart. And even many of these instruments not measure beyond OD6, 7ā¦ thatās why many charts are cut off at the top. But anything at or above OD6 is OK for us.
I was looking for dual purpose glasses (a have a fiber laser at 1080nm and also a CO2 laser on 10600nm) found an OD7+ for both wavelengths with good VLT (visual light transmittance) almost clear lenses (slightly blue) for ā¬168 net. There were cheaper alternatives for either one blocked wavelength or less VLT.
Cautionary tale:
I got mine from Phillips through Amazon (āshipped from and sold by amazon.comā), but my ābuy it againā link now goes to an allegedly identical thing āsold by Cellar Door Booksā. Yeah, I might get the same thing, but Iām not at all confident.
The official Phillips Safety site has choices:
And on Amazon:
https://www.amazon.com/s?k=laser&me=AHG385SWWW6L7
Be very careful who you buy from, as Amazon really makes that hard to verify. AliExpress / eBay / whatever seem even worse.
Buy a second pair for the friend who drops in to see what youāre doing with your laser, because it would be nice if they left in the same condition. 
Thanks all for the responses, I think Iām better equipped now to shop for and buy what I need.
Wg
WOW, this is confusing my brain!! Does the lens color matter? The machine came with dark green glasses (very uncomfortable). I ordered some with amber lenses, but now I question that purchase.
Arg!!
Wg
If I understand correctly, the AtomStack A20 PRO has a 445 nm laser, which is in the blue-violet end of the spectrum. Because the laser light is visible, it will pass directly through your cornea to your retina, whereupon Bad Thingsā¢ will happen.
The visible color of the lens in the glasses doesnāt matter nearly as much as its ability to block the specific wavelength (ācolorā) of the laser light. That ability is given by the OD (āoptical densityā) value, the logarithm of the attenuation: OD 6 means an attenuation of 10ā¶ = 1 million.
My COā laser operates at 10.6 Āµm, deep in the infrared. A lens with OD 6 attenuation at 10.6 Āµm is perfectly clear in visible wavelengths and is, in fact, pretty much ordinary polycarbonate plastic.
If the glasses packed with the Atomstack have their OD value at 445 nm printed on them, then thereās a faint chance they are actually doing what you expect. However, because they pass green light, with a wavelength around 555 nm, Iād expect they have little attenuation for blue light at 445 nm.
Without knowing anything more about them, I would lay big money that theyāre the cheapest fancy-looking sunglasses available, have little-to-no attenuation at 445 nm, and are junk for that particular laser. Iād love to lose that bet.
Feeding 445 nm into the Phillips calculator produces an assortment of safety glasses, with the least expensive ones in their AKP series:
Note that theyāre all orange tinted polycarbonate, rather than green.
Not cheap, but right now you have all the eyes you will ever get.
Thank you, this is very reassuring. The glasses that came with the machine are not fancy, just big! I canāt find any markings at all so presumably they are just dark glasses. When I get set up with other eyewear, Iāll try the laser on the current ones. If I understand correctly, if they burn - they block the light.
Thanks again!
Wg
That is both correct and dead wrong.
The real question is how much light passes through to your eyes. A lens that absorbs enough energy to burn itself does not mean it absorbed enough energy to prevent damage to your eyes from whatās left.
I think youāre on the right track by getting spendy eyewear from a reliable source and I sincerely hope youāll never need to know well it works!
(a have a fiber laser at 1080nm and also a CO2 laser on 10600nm) found an OD7+ for both wavelengths with good VLT (visual light transmittance) almost clear lenses (slightly blue) for ā¬168 net.
Can you please share a link/name/anything of the glasses you found? Iām searching glasses for the same purpose right now.
Make certain no matter what anyone here recommends, that what you use offers good protection. Trying to attach a screenshot of what I bought.
Best always!
Wally g.
Iām thinking of these:
Same as @ZsBela I need the glasses to protect against both fiber and co2.
Phillips makes great products. Good choice.
Wg
Hi, my glasses are a product of Phillips Safety Products Inc (not to confuse with the well-known Philips (single L ) Electronics)
I bough a KG5 Series glasses
One of these: KG5 Laser Safety Glasses | Phillips Safety (phillips-safety.com)
I live in Germany, so I actually bought mine on the German Amazon amazon.de
(so I had fast and free shipping and no hassle with the customs, otherwise I would have to order it from the USA)
For those in Europe, this is the product on Amazon:
Laserschutzbrille AKG-5 Holmium/Yag/Co2 ā Modell #33-BK : Amazon.de: Baumarkt
Great glasses (the lenses) but what concerns the frame (not so great) I did these modifications:
I believe the A20 Pro already comes with safety glasses. Plus it already has a safety shield around the laser head so unless you are doing glassware you donāt need the safety glasses
