BluBlockers vs Red Safety Glasses (Pics Included)

[TheDukeAnumber1]

I've got the comparison pictures shown below using a 1.8W 445nm laser, and to sum it up. BluBlocker sunglasses are nearly as good as the standard red safety glasses. The red glasses outclass the BluBlockers when it comes to upclose focused burning, if your burning a light colored surface with blublockers you'll get some afterimage lasting only seconds but still unhealthy and can be avoided using the reds. When it comes to distance burning BluBlockers work well and don't leave you with afterimage.

Where the blublockers shine is they are easier to take with you and prevent you from looking like a complete dork lol.

So Blublockers will protect you from slight exposure to 1.8W 445nm blue (and probably violet lasers aswell) but the cheap reds are safer.

Straight 1.8W 445nm blue.

Polarised BluBlocker brand sunglasses

Standard Red Safety Glasses

 

[ElectroMagneticFreak]

It does look like it is stopping it somewhat. But the telltale sign that it is not doing enough is the fact that you can still see blue (which you should not see at all) through both those glasses.

With adequate goggles you should only see a whitish spot through the glasses and no blue at all, and with both those glasses there appears to be blue coming through.

The white color spot that you should see is I believe the glasses fluorescing where the laser light is hitting it, but there is no laser light actually coming through. However when you see blue it tells you that there is laser light getting through to your eyes.

The polarized sunglasses definitely will offer no protection from a reflection and most likely do not block enough light even to look at the spot either...

I am curious to know what the veterans think about this but I highly doubt that they would consider those adequate for laser protection unfortunately...

Also, in general any kind of sunglasses, welding goggles etc. are never recommended as there are far too many noobs unfortunately that will think they can get away with buying a laser on the internet and use their dads welding goggles or sunglasses thinking that will be enough and that their sunglasses or whatever (because they think they are high-end) will be enough... It's just a really good way to get permanent eye damage with a false sense of confidence...

 

[InfinitusEquitas]

I tested both the blublocker goggles, and the "red" cheapo goggles.

IMO neither are a good option, although both will protect from diffuse reflection, and are better than nothing.

 

[Molo]

But the telltale sign that it is not doing enough is the fact that you can still see blue (which you should not see at all) through both those glasses

Yea I wouldn't recommend any glasses/goggles that you can still see your lasers color through.

 

[InfinitusEquitas]

Yea I wouldn't recommend any glasses/goggles that you can still see your lasers color through.

That's not really a good assumption to make either.

The human eye is EXTREMELY sensitive to green light for example, using goggles that are perfectly safe for use with green (532nm) lasers you may still see a hint of color.

The same same holds true for goggles used for red lasers, the red color is still quite visible, even though the user is perfectly safe.

Bottom line is to test out goggles, at the very least, you need to have goggles you already know are safe to use (meaning certified) and a decent laser power meter. Even then it's a bit of a gamble imo.

 

[ElectroMagneticFreak]

That's not really a good assumption to make either.

The human eye is EXTREMELY sensitive to green light for example, using goggles that are perfectly safe for use with green (532nm) lasers you may still see a hint of color.

The same same holds true for goggles used for red lasers, the red color is still quite visible, even though the user is perfectly safe.

That is really interesting what you are saying about certain laser wavelengths and their color still being visible such as green and red despite the goggles adequate protection.

It makes sense for green since it is near the peak of color sensitivity, but for red why would this be I wonder? Also most common red handhelds (650nm) that we have access to have far less power (<300mW) than say 1W+ 445nm blue where the goggles are able to absorb pretty much all the blue light and we only see a whitish or orangish spot depending on the goggles color.

Is this due to the fact that the pigments used in 445nm blue absorbing goggles are more efficient than those for absorbing red lasers? Based on mW power most often used with 445nm along with relative brightness it would seem that 445nm blue color would be more likely to be seen through goggles and that 650nm red would be the least likely to see the color through.

Just seems counter intuitive I guess. I only have the Eagle Pair 405nm- 532nm goggles but have some Dragon Lasers green colored red laser protection goggles coming in the mail so I am curious to try and see if I can still see some red like you mentioned.

 

[grainde]

I posted something on this for the eagle pairs a while ago: Caution Eagle Pair. At the time of posting I didnt have access to an LPM, but subsequent testing in the thread showed that green even at 5 mW was visible through the glasses, but in actual fact nothing could be registered on the LPM.

I have seen exactly the same for my 580 - 760 nm EPs. When I shine a 188 mW 650 or even a 520 mW 635 through them I can clearly see the dot. On an LPM however nothing is registered.

The OD vs Wavelength graph for the 190-540nm EPs actually gives an OD of around 5.5 for 445 and OD 6 for 405, where as at 532 its closer to 3.5 than 4. EP 190 -540

I havent been able to find the actual graph for the 580 - 760 EPs (listed as EP13 on SL website and EP11 on the eagle pair site), but the EP2s are probably very similar if not the same. These have an OD of 3 at 635 and OD of <4 at 650.

So it is probably a combination of both the visibility of the wavelength used vs the actual OD of the glasses at that wavelength. I know for 405 and 445 many materials will absorb these wavelengths and fluoresce. As fluorescence is shifted to longer wavelengths the fluorescence dot will be clearly seen through the goggles. This means the OD can be very high but the dot will still be visible. At the lower energies or longer wavelengths however, (green through to red and IR) fluorescence is much less common (normally have non-radiative decay eg vibrational relaxation etc) and so if the glasses were made to block more of the light ie higher OD the spot would be difficult to see. :beer:

 

[ElectroMagneticFreak]

That is very interesting and some useful insight, thanks Grainde.

So part of the lack of visibility of the color through orange goggles in shorter wavelengths like 445nm is due to the fluorescence created which overpowers some of the blue that could be visible?

The only wavelengths I look at the dot close range with the orange colored Eagle Pair that I have are 445nm and 405nm, and the dot is always white. I have a green LED flashlight and the bright green color is white through the goggles. I guess it's not bright enough for the green to show through even with the lower OD at 532nm. The white color that the green LED light becomes, is that a fluorescing effect, although it would be out of the range of fluorescing capability as you were mentioning. If it looks white through the goggles is there another mechanism for this other than fluorescence?

As for a 650nm laser, is it not possible to have the OD high enough to make the dot look white through the goggles, and does it just remain red at higher OD's until it finally is just invisible because of the lack of fluorescing effect on the goggles with red wavelengths that would otherwise make the dot look white?

I am really looking forward to getting my green colored red absorbing goggles from Dragon Lasers to see how their goggles perform and what the dot looks like with 650nm light.

 

[grainde]

So part of the lack of visibility of the color through orange goggles in shorter wavelengths like 445nm is due to the fluorescence created which overpowers some of the blue that could be visible?

This could also be the case, although I wasnt actually saying that! But yes the fluorescence could overpower any blue that would otherwise be visible. The combined wavelengths blue + fluorescence would appear more "white".

I was actually saying with the high OD in the blue the glasses let very little light through (445 & 405) and this coupled with the fact we have less sensitivity to these wavelengths would make a weak blue dot much harder to see. Again as you mentioned this weak blue would be then over powered by the fluorescence.

I have a green LED flashlight and the bright green color is white through the goggles. I guess it's not bright enough for the green to show through even with the lower OD at 532nm.
The white color that the green LED light becomes, is that a fluorescing effect, although it would be out of the range of fluorescing capability as you were mentioning. If it looks white through the goggles is there another mechanism for this other than fluorescence?

I cant categorically confirm this, but yes its possible that it's fluorescence mixed with green, as red light + green light gives yellow. So does the light appear white or yellow? With my 5 mW green through the glasses it appears yellow! Below is a general explanation of fluorescence:

Fluorescence can still occur with 532 but it is less common and even less so with red and IR. It will depend on the material absorbing the photons and its fluorescence quantum yield. Normally if you absorb a photon the transition is from a vibrationally excited ground state (Eo) to the first excited state (E1) also in a vibrationally excited state. This E1 then relaxes back to the vibrational ground state of E1 thus loosing some energy. Hence why emission (fluorescence) is at longer wavelengths.
If there is a good overlap of the wavefunctions between E1 and Eo there is a high probability of quick relaxation of the electron back to the ground state Eo and this can result in the emission of a photon at longer wavelength, if there is a large energy separation between the 2 electronic states. If the energy gap is small, ie in molecules excited by low energy photons, significant kinetic competition between internal conversion and fluorescence exists and much less radiative emission is seen.

As for a 650nm laser, is it not possible to have the OD high enough to make the dot look white through the goggles, it just remains red at higher OD's until it finally is just invisible because of the lack of fluorescing effect on the goggles with red wavelengths that would otherwise make the dot look white?

As there is negligible fluorescence at 650, effectively the only light youll see through the goggles from the dot will originate from the beam itself. If you increase the OD of the red glasses, which is easy to do (increase the concentration of dye molecules in the plastic) this red light will be much less visible to the point of you no longer being able to see the dot. As we need to see where we are pointing the OD is kept lower so we can still see some light.

I am really looking forward to getting my green colored red absorbing goggles from Dragon Lasers to see how their goggles act with 650nm light.

Id be interested to see the results! :beer:


Edit: Just had a look around and here is some further info if you're interested. Contains some pictorial representations with explanations: http://en.wikipedia.org/wiki/Franck–Condon_principle

 

[Benm]

So part of the lack of visibility of the color through orange goggles in shorter wavelengths like 445nm is due to the fluorescence created which overpowers some of the blue that could be visible?

Absolutely. In fact, it is the only way you can see the light from a blue/bluray laser as white or any other color other than what the laser is emitting. This goes for orange or red goggles equally.

For red lasers its a different story entirely: Fluorescense will never produce a whavelength shorter then the laser outputs. You would need a nonlinear process for that, where 2 or more photons are combined and one of higher energy is emitted - similar to what happens in de doubling crystal of a green laser.

The only reason the dot from a red laser may appear orange, yellow or even white is heat: If you heat up the target to a temperature where its blackbody radiation is in the visible range, you can see that light. This isnt easy to do with thermally conductive materials, but you sometimes see the occasional shimmer when toasting cardboard with a red laser (and it will work with IR too).

 

[ElectroMagneticFreak]

Grainde and Benm,

Thanks very much for the time you took to explain all of that, it was very interesting to read and really helped my understanding.

I am always amazed at the minds here on LPF, there are so many knowledgeable people here. I think if everyone here got together and formed and organization there would be a tech Giant with more expertise than NASA!

@TheDukeAnumber1 I hope you don't mind the follow up questions on the thread, your post brought up some interesting questions about the characteristics of the dot's visibility through glasses and how this appearance changes with wavelength.

:thanks:

 

[TheDukeAnumber1]

No problem, its all about the advancement of the hobby isn't it

I've read through the posts and appreciate learning from the experience of others and this discussion has made me decide that my next laser purchase won't be on an actual laser, but on a better pair of laser glasses.

 

[spacebirdfameus]

This was a very helpful thread!!

 

[TheDukeAnumber1]

Ty, also worth noting the blublockers I used were polarized and were just ok for 445nm, but when I tried non-polarized blublockers they actually worked very well for 445nm.

http://laserpointerforums.com/f52/blublocker-vipers-vs-uvex-goggles-80639.html