It is sometimes required to reduce the power of visible lasers to an eye-safe level while still allowing visibility for alignment purposes. Laser goggles are designed to provide a very high level of protection with optical densities (OD's) of 4, 5, 6 and 7 which completely block out the laser making the spot invisible and therefore unable to be aligned.
In this situation, you will need to use laser safety glasses specifically with low optical densities such an OD 1.5 to cut 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 safety glasses such as the LG-006, LG-006N and LG-007 in the below links are made for low power visible lasers. Due to the various factors involved it is best to talk with a laser safety expert to work out the best option. Should you wish to speak with one of our experts email us at info@dioptika.com
http://www.lasersafetyglasses.com.au/lg-006-red-la...