Sometimes it is desirable to cut down the power of visible red or green lasers to an eye-safe level while still allowing visibility of the laser spot for alignment purposes. Laser glasses are generally designed to provide a very high level of protection with optical densities (OD's) of 4, 5, 6 and 7 that will typically block the visibility of the laser spot or line out completely therefore making it un-useable while wearing the glasses.

For this purpose, laser safety glasses have been designed specifically to have low optical densities such an OD 1.5 which cuts down the laser power by ~ 30X. The visibility of a laser spot to the eye also varies with how much ambient light there is. For example if the laser spot is in direct sunlight, then the laser will need to be cut down significantly less than if it was in the shade or indoors. Other things to consideration are the size of the laser beam, wavelength and shape.

The LG-006 and LG-007 laser safety glasses shown in the below links are specifically designed for low power visible lasers. 

http://www.certified-laser-eyewear.com/lg-007-red-...

Due to the various factors involved it is best to talk with a laser safety eyewear specialist to work out the best option. Should you wish to speak with one of our experts feel free to email us at info@dioptika.com