Often it is desirable to cut down the power of visible lasers to an eye-safe level while still allowing visibility of the laser spot for alignment purposes. Most laser glasses are designed to provide a very high level of protection with optical densities (OD's) of 4, 5, 6 and 7 and will typically wholly block out the laser making the spot invisible and therefore unable to be aligned.
For this purpose, you will need to use laser safety glasses specifically made to have low optical densities such an OD 1.5 which cuts down the laser power by ~ 30X. How visible a laser spot is to the eye also varies with how much ambient light there is. 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 considerations for visibility are the laser beam size, wavelength and shape.
Laser glasses such as the LG-006, LG-006N and LG-007 shown in the below links are specifically designed for low power visible lasers. 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 call us on 1300 411 337 or email us at info@dioptika.com
http://www.lasersafetyglasses.com.au/lg-006-red-la...