OD - A question

I have a question about some glasses I'm looking to get.

The laser diode I'll be working with is a 2Watt 808nm diode, in a very thin parallel beam.

Go on Ebay and look for item number 150175930288.

In particular, it says:
"808nm-850nm Diode Laser OD= 2" and "Once you put this goggle on, you shouldn't be able to see the laser light at all unless otherwise. If you do, please turn off the laser immediately as the goggle is either defective ! Contact us immediately."

Firstly will an OD of 2 (1%) be enough for this laser diode, bearing in mind that I will need to align it.

Secondly, it says that if I can see the laser then there is a fault - If this is so, how am I ment to align it ? (I know it's infrared and I need one of those little cards to be able to see the colour.)

Thanks.

There is no reason to have low OD when you are working with UV or IR since you cannot see them anyway. OD 6 or higher is recommended as you don't want any IR transmission from your laser. If you use OD 2 with a 2Watt laser your eyes will be exposed to 20mW 808nm. You wouldn't shine a 20mW greenie in your eye you certainly don't want 20mW of IR in your eye. Of course this is only on a direct exposure but you can imagine the probability of a direct exposure to an invisible beam is much higher than a visible beam.

I realize you can view a dull red color from the 808nm but what is visible is only a very small amount of the output power. Protect your eyes a bit more. Using an IR detector card will allow you to visualize the location just fine.

You can look at these. A bit more expensive but high OD, good VLT and FDA/CE certified.

http://store.oemlasersystems.com/index.php?main_page=product_info&cPath=32_7_16&products_id=223

Thank you for your help, I didn't think about the cards giving off a different wavelength. I will have to wait till I get some more money.

oh there is an LPF discount (7.5%) if you include the coupon code NOR200801 on checkout.

Cheers, I'll make a note of that.

this is a great thread and i say sticky it for future references and easy finding!

the goggles i offer are od4 and i really like them!

i have a group buy going for the532nm ones and also the 450-650nm multi wavelength ones!

check my sig for the link

So I have noticed that when you choose goggles some are specific to the laser element ( Alexandrite, YAG, DI3 diode, Argon...)

Is this important?

I have noticed that some of the brands like the Dragon Laser Goggles don't tell you.

What is important is the wavelength rating. When you see Argon, or Alexandrite, or YAG that just tells the person what kind of lasers they protect against as most know the type of laser they use but may not be aware of all the wavelengths the laser radiates.

If the rating, for example, is OD7 @ 400-540nm and it's listed as Argon protection it can still be used for 405nm, 473nm, 457nm, 532nm in addition to the argon lines.

Hello, I have a pair of red goggles I bought just to see better the red laser dot of a laser level. They are a good goggles, they cost me nearly 60€. They are HILTI brand ¿you know it?, they sell tools for construction. Now I have proved this goggles with my green 50mw and you don´t see the light. Just a little red dot in the floor, th green laser turn into red. If you point laser beam directly to de goggles,it just bounce, no % of the beam pass throug the lens. But I don´t know if they are ok to protect me from IR. I don´t know if the IR pass trhoug the lens or not.
Another question about IR. Obviously i won´t point directly to the eyes, but, ¿how bad it´s to look the laser beam pointing to a wall? I mean a white wall that reflects a big amount of light or any other surface that reflects the light, not the beam, just the light.
Thanks