How Much Laser Power Gets Through Goggles

[Nutball]

I have always wondered how much laser power can get through Goggles. Just out of plain curiosity, and also perhaps for more practical applications. Even knowing the answer may help others be more cautious even when wearing goggles if a lot can get through.

Anyway I thought it would be nice to have a reference thread where we can post results for various wavelengths and goggle brands and laser powers/beam sizes...

Picture is just because. 650nm @ 100~250mW, 532nm @ ~70mW


So, if y'all need an excuse to pull your lasers, meters, and goggles out again, test and post away

 

[Immo1282]

I'll definitely be doing this with the goggles I got from Sanwu with my Guardian 1W when I've finished building an LPM. I haven't found any independent information on whether they're good or not so I'm keen to test it myself...

 

[GSS]

Are those the ones rated for all wave lengths from 200nm to 2000nm that we see lately or the 200nm to 450nm?

 

[Nutball]

In my pic are Green goggles from Sanwu. They have the look of a cheap chinese standard for laser goggles. They do a good job of blocking red, but as you can see, I'd guess up to around 5mW still gets through. Not bad, but what if a 1W red hits it?

 

[GSS]

Then Sanwu sell those for 405 and blue lasers..
They have to be identical to the claimed all wavelength one's on ebay??

 

[Immo1282]

They were on my order confirmation written down as "Color: Red (445nm470nm, 520nm532mn)"

 

[Nutball]

I think my greens were for 650,638, & 405 if I remember correctly. They look just like a red pair I just ordered on ebay to block 532nm.

EDIT: I just checked Sanwu's website. These red and green goggles reduce power by a supposed factor of 1000. So, only a max of 0.25mW of red should get through. I think that looks reasonable according to my picture above. Even 7W should be reduced to 7mW, which helps a ton. LPM data would still be nice.

 

[GSS]

They were on my order confirmation written down as "Color: Red (445nm470nm, 520nm532mn)"

It might be red for the lens color, not wavelength.
Usually blue lenses are for red laser's, and even though the green lens might stop a little of the red laser, Nutball I think 250mW is the max limit, probably to much and yes a meter will tell..
I have also played with my cheapie glasses with different color lasers. Iv'e learned the cheap blue "lens" glasses do absolutely nothing to stop a 650nm. Iv'e been told they might be ok with the 638nm??
Iv'e tested cheapie green and blue lensed glasses with up to 5W+ of 450nm and they were actually ok and even held up to 30 or 40 seconds.
I won 3 different pairs at $1.25 each at auction just to test them. They have nil quality control if even at all. Some were thicker than others also in the same style ebay frame. Best to test the side protection lenses they have if you want to ever use them.

 

[Nutball]

I have burned my glasses before, but that was when I focused the 650nm 250mW to 3" distance to see if I could burn them. It just left some tiny surface melt marks

 

[brendon7358]

I have tested goggles before (I sell them if anyone's interested) and I can test goggles if you send them to me. Looking at that picture I would not trust those for anything. A good pair of goggles should let so little light through you can barely see it.

 

[smallfreak]

An interesting idea. I got a set of cheap goggles in three colors. Dark-red, light-red and green. I skip the green one, as the green beam passes right through it, as one might expect.

Laser: 532nm, labelled < 50mW, unmeasured.

shot in bright light without filter. This shows my "light red" goggles


Now shot through the goggles:



There is some light passing, but the spot is quite faint. So I took another shot with lights off:



OK, should be safe in the optical - no idea how they perform in the IR to block residual light from the Diode and YAG. Probably not so good.

Now to my "dark red" goggles in same lighting conditions:



Nada. Nothing. Completely blocked. No traces, even in the dark. Let's try the other way and WATCH the spot through these goggles:



Quite visible red spot, even in normal lighting. This is definitely not the primary light. The "light red" goggles show a yellowish-green spot. The "dark red" shows a red dot as demonstrated. Certainly the red part of the flourescence induced by the green beam.

 

[paul1598419]

I agree that this pair of goggles doesn't seem to work well at all. I seriously doubt they cut the power by a factor of 1000. I have several pairs of green colored goggles and at 300 mW of red laser light, none gets through to leave a spot on anything going through them. For some reason, blue colored goggles don't work as well for red as green ones do. It is rare to see a blue pair of goggles that have an OD higher than 2 or 3 for red.

 

[brendon7358]

Blocking red is difficult for some reason. I have never seen a cheap pair that does it well. My eagle pair does, they are a brownish, yellow color.

 

[Nutball]

Guess I shoulda got dark red.

I have used my eclipse glasses when trying to light a black match with my green laser to see if it could. It was hard to keep the laser on the match it was so dark. It looks like <1mW gets through them. They do burn easy.





The laser wasn't aimed at the camera, but it would have appeared extremely bright head on as I'm sure even a 1mW laser would appear to us head on.

 

[paul1598419]

That is a perfect example of why you should never use those cheap solar eclipse glasses as laser safety goggles.

 

[Benm]

Obviously not - if that laser beam had a bit more power to it, it would burn a hole straight through.

Those eclipse goggles are exactly built for that single purpose, but the lenses on them are often wafer thin. Thick enough not to melt under direct sunlight, but thin enough to blast through it a few watts of laser light in under a second.

As far as optical density goes: do you really need anything beyond OD3? If you consider the blink reflex would protect you from exposures under 5 mW, OD3 goggles would suffice up to a power level of 5 watts, providing all that light is going into your pupil.

This is perhaps theoretically possible if you would look straight into the laser from close range whilst wearing those goggles, but that'd be an incredibly stupid thing to do in the first place. If you want protection from accidental reflections from windows and shiny things your risk is -greatly- reduced by OD3 or even OD2 protection.