durration of exposure with goggles/glasses

[leftkidney]

these goggles say

"Utilizing non-reflective technology, energy is absorbed for a minimum of 10 seconds at the maximum power density for the OD or L rating before loss of protection and will not photo-bleach or degrade over time."

so 10 seconds min, but what about the maximum? shouldnt it say the maximum, who needs to know the minimum that something can protect you its the max protection you are looking for - like getting a radiation suite and having it say it will protect you for a minimum if 10 minutes, so what after 11 minutes you have problems or after 20 hours you have problems, you need to know thi s stuff when it comes to safety

also I have been told that these are the best out there for the 445nm laser I will have, dont care about price because its my eyes I want to protect and would rather pay more for the same thing because it makes me feel better, lol

what about taking 2 pairs of these, like the glasses and goggles and wearing both of them, would it double the protection? - or should I just cover them up after 30 seconds or so to let them recover like my "laser dudes" do?


I have some "laser dudes" who work at IBM with me but I dont really know them and they are in a different building I dont have access to so I only see them every once in a while so I have to ask here and wait until I see them next - they work with really high powered lasers mostly gas lasers - I have been told that they will cover up there goggles with there hand after a while if the lasers arent turned off for a while, or put them under there lab coats to block the light so they can recover - but again they use really high powered gas lasers that are like 405-650nm and some that are IR/UV so I am not sure if this applies to the lasers we use

 

[Benm]

Its a bit odd, it doesnt say what the maximum power density actually is.

 

[leftkidney]

Its a bit odd, it doesnt say what the maximum power density actually is.

yea what I was thinking also - but being a OD 7+ they are probably great

I remember seeing a review of goggles and I searched for it but cant find it anymore, they showed these and 3 others

 

[HIMNL9]

always remember that protective goggles are not planned for permit you to stay looking in the beam for "x" seconds, they are planned for protect your eyes in case of accidental reflections .....

I mean, it have no sense, for a protective goggles seller, to say "with these goggles you can stare in the beam for 10 seconds" or similar, cause it's not their purpose .....

 

[Benm]

No, but it would be guaranteed that a beam of power(density) x will not chew through the goggles within y seconds. Lets say you had very thin glasses with high optical density, and you are working on a 1 watt 445 laser. That would likely melt a hole through within a second (like electrical tape or a cd case), so those glasses would be inadequate, despite the initial optical density being high enough.

Also, optical density is a bit of a choice. It should be 3 to work with up to 1 watt of power. You should consider if you really want something OD6 or more: you can hardly make out the dot with those, making them impossible to work with when you want to align a set of mirrors/dichros and such.

 

[HIMNL9]

^ oh, in this sense yes, i agree with you, it make sense also speaking about time :beer:

 

[FrothyChimp]

The 10 second rating is the standard for OD testing. Laser eye protection is not designed for you to look into the beam all day. The 10 second rating is the OD versus a laser that takes 10 seconds at 10cm to melt through the lenses or 100 pulses. When they are tested in the lab each sample is subjected to higher and higher power until it takes exactly 10 seconds to destroy the absorptive dyes. At that point the OD is measured and assessed for that particular lens. they do this with each wavelength the lens is to be protective against. There is also a safety factor applied on top of the measurement.

Remember the ratings are for a direct exposure or specular exposure. Wearing protective lenses in diffuse laser lighting does not affect the dyes and you can wear them all day without damaging them.

This is, of course, only for real laser safety eye wear. If it doesn't have a certification as ANSI Z136 or CE EN207 approved it's not real...ever...no exceptions. I don't care how well some shade or another works. If it doesn't have the cert it's not safety eye wear simply because you have no clue when it will fail.

 

[leftkidney]

always remember that protective goggles are not planned for permit you to stay looking in the beam for "x" seconds, they are planned for protect your eyes in case of accidental reflections .....

I mean, it have no sense, for a protective goggles seller, to say "with these goggles you can stare in the beam for 10 seconds" or similar, cause it's not their purpose .....

since most people that are here using lasers that are handheld and have goggles they are burning things - so how long can you look at what you are burning before it becomes a problem

also are those glasses I linked to certified? - I have not seen anything on the site but that doesent mean they arent

http://store.oemlasersystems.com/index.php?main_page=product_info&cPath=10_12&products_id=7

 

[Tech_Junkie]

Frothy owns OEM lasers.

I have the same goggles, and they work great for burning.

Yes they are certified. Best goggles on the market IMO.

 

[leftkidney]

so about my other question, does wearing 2 pairs make double protection - like the goggles and glasses, you know like those old people who wear the huge sunglasses over there normal glasses

 

[leftkidney]

just noticed that they are in East Lansing MI and I am in Detroit - do they have a location I can go and buy from so I dont have to get them shipped and save on shipping

 

[leftkidney]

so what about the aixiz ones - AixiZ they dont even have info about exposure or weather they are reflective or absorptive

anyone know about that

 

[Benm]

The 10 second rating is the standard for OD testing. Laser eye protection is not designed for you to look into the beam all day. The 10 second rating is the OD versus a laser that takes 10 seconds at 10cm to melt through the lenses or 100 pulses. When they are tested in the lab each sample is subjected to higher and higher power until it takes exactly 10 seconds to destroy the absorptive dyes. At that point the OD is measured and assessed for that particular lens. they do this with each wavelength the lens is to be protective against. There is also a safety factor applied on top of the measurement.

Interesting, but it still does not answer the simple question: what power (or pulse energy) is that laser? I'm sure all plastic lenses have OD zero (i.e. a hole) after exposure to a kilowatt/mm2 for 10 seconds, but what about one watt, or ten? I never see that power rating anywhere, but it is an important aspect aside from OD 'out of the bag'.

This is, of course, only for real laser safety eye wear. If it doesn't have a certification as ANSI Z136 or CE EN207 approved it's not real...ever...no exceptions. I don't care how well some shade or another works. If it doesn't have the cert it's not safety eye wear simply because you have no clue when it will fail.

You have to be careful to read those certifications too. O-like goggles come stamped with ansi Z87.1, which is a standard for mechanical strength for safety glasses. It basically means that the glasses are fine to wear when you are taking a chainsaw through a tree, but says nothing at all about performance with lasers. Interestingly, they are also marked 'laser use only', which would give the user the impression that the standard would apply to that.

Not that those glasses are bad though, it took over a minute to chew through one with near-1W 445 laser. It doesnt bleach out, just melts through eventually... but the standards stamped are just wrong.

 

[Benm]

so about my other question, does wearing 2 pairs make double protection - like the goggles and glasses, you know like those old people who wear the huge sunglasses over there normal glasses

2 pairs on top of eachother will result in double OD, so in theory, you could consider that double protection. It would also take twice as long to melt through two pairs of goggles instead of one. It doesnt seem very practical though.

 

[FrothyChimp]

Re: duration of exposure with goggles/glasses

The power rating of the lasers used to test lenses for certification are never indicated because the actual calculations used to determine the OD required for a particular laser take into account the wavelength and power/energy of the laser. Then it's just a matter of selecting an OD higher than the results of the calculation. The lasers used in certification and output powers do nothing more than validate the standard so they are not published.

I've posted the calculation for determining OD somewhere on the forums before. It's not the simple log10 calculation but the one that takes into consideration the time interval, the power/energy, MPE (maximum permissible exposure) and the wavelength. That's the calculation that LSOs use.

Regarding the Z87.1 standard, if that's all there is then they are nothing more than tinted impact safety glasses. You might as well just go to Home Depot and buy a colored pair there. They are probably cheaper. Of course, they are still are not laser protective but I guess it's not my eyes. I just don't understand why someone would buy a "real" laser and not buy "real" protection. It's the same as repelling a mountain without a repelling seat. If you slip, the result is life altering and permanent. I know, I know, I've heard it before, "I'm safe with my lasers, it'll never happen to me."

I'm cynical because I keep seeing the same idiotic claims, yet each year the lasers get more and more powerful. Your average ignorant teen with a job at McDonald's (or worse, the, "I deserve money from my mommy and daddy and never earned anything in my life", teen) can now afford a class 4 laser every bit as dangerous as those the professionals lock away in class 4 rooms in laboratories and LSOs fret over.

At least my eyes will be fine. I always use certified laser eye protection. Sorry for the rant. /rantoff

 

[Benm]

I agree with your concerns, to i proceeded to test what actually happens during a sustained laser blast through these goggles.

You can easily say that some product that has not been tested is no more useful than a pair of coloured sunglasses. This may or may not be the case. But in reality, the testing procedure and fees are so expensive that manufacturers will choose not to perform them, even if the product would pass with flying colours.

Certification is nice for those who need it in order to get insurance etc, but offers very limited benefit beyond that in some cases. Especially items manufactured in smaller quantities are things that go without certification - otherwise the final product cost would consist of 99% certification cost, making the product entirely non competitive.