If you don't require hardcore certification and are just looking a peace of mind kind of thing, you can even try a local college/university. They would likely do it for free and consider it a unique lab experience for their students.
If you are planning on selling them, you would be wise to serialize each one, test individually, and prove/supply the test results of that particular pair to the user of that particular pair. Measured OD levels can vary by quite a bit even within the same batch. This will ensure that you are selling what you are advertising, and will add value to your final product. Regardless, you cannot guarantee protection without expensive lab certifications, but you can at least educate and offer a cheaper "good enough" alternative.
All you need is a laser power meter. You can measure the power of the laser, then measure the power of the laser after it has passed through the goggles. Now, divide the power of the laser by the power of the laser that made it through the goggles. Now, take the log of that rational number to get the optical density. I don't know how to write formulas in here, but where Pi = initial power output of laser and Pt = total power of laser, OD = log(Pi/Pt) Don't forget, length of radiation (as in, how many seconds the laser is shining through the goggles) also plays a part in how safe goggles are. The goggles can have a great absorption OD number, but some dyes break down more quickly than others, some plastics burn/melt faster than others. You might want to do some destructive testing on one pair to get an idea of how long it takes for the protective quality of the goggles to become compromised.
Last edited by bshanahan14rulz; 05-31-2012 at 12:51 PM.