New Safety Goggles needed, help me translate mathematics please ;-)

Hi,

I do need new safety goggles because mine have an OD higher than needed.

When using my safety goggles, I can only see the dot if projected to a white surface, and even doing this it's still very hard to see anything... let me explain :

- If i do know before using my goggles where the beam spot will be on the white wall then I will be able to see it, but it's a very dimmed spot which is way dimmer than a simple candle flamme.

- If i don't know before using my goggles where the beam spot will be on the white wall then I'm not able to find it without putting my goggles off...and i don't want to do that.

This can be dangerous because I can't have any control of what's happening.

After search i just found this :

OD = log[sub]10[/sub](E[sub]i[/sub]/E[sub]t[/sub])

But i don't understand how to calculate this, does someone can help me ?

Here is my example:

Laser Maximum Output: 230mW
Maximum Needed Transmitted Power: 1mW

OD = log[sub]10[/sub](230mW/1mW)

OD = log[sub]10[/sub](230)

OD = ??? ( i don't understand the "[sub]" and the "[/sub]" things... :yabbem: )


Other useful informations :

My red laser is a 650nm, 230mw powerchecked from Odicforce.com
My actual safety goggles are :
Eagle pair 190-380&600-760nm OD4+ CE

On a goggles certificate paper I can see:

Fourth harmonic generation, 266nm OD5
He-Ne laser emitter, 632.8nm OD4
Ruby laser emitter, 694nm OD4
Alexandrite last emitter, 755nm, OD4

log(230/1) = 2.36 OD.

A simple approximation is divide the power by 10^(OD). So right away with no calculator you can see you need OD2 for 2.3mW and OD3 for 0.23mW. Just round up for simplicity (and extra safety) and get something OD3 or more.

I think they thought that VBulletin would change the [sub][/sub] into a subscript. to look something like this. But this forum doesn't have some of those things..



Also: 10^(-OD) * Laser mW = mW to eyes
If you don't have a fancy TI calc you can use wolframalfa.

^Or Google.

That is a very useful trick!

hi,

Thanks for all theses answers, verry informative and usefull.

So giving the advices I would like to find OD2.5 safety glasses for 630nm-680nm.

I do not want another Eagle Pair, mine is inconsistent between left and right glass (right glass has a higher OD than left one).

I'm willing to spend as much as 150$ for this but still unable to find what i'm looking for on theses websites :

OEM Laser Systems
Laser Safety Industries
Thor Labs
Suvival Laser

Any ideas ?