It's nominal ocular hazard distance is about 900 feet / 280 meters when collimated properly. That is no joke. About three to five times a year I have to explain to users of blue diodes what to tell their Doctors in order to get rapid treatment by an Opthalmic Surgeon and what is needed to reduce swelling/bleeding in the back of the eye in order to save what is left.
If you want to risk your vision, that is a shame. If you are careless and wish to risk the vision of others around you, that is just beyond my comprehension.
You need tested and certified Goggles of at least Optical Density (OD) six and complete control over entry to the room where you use the laser. Even for scattered light.
For best results your experiment should be totally contained in a metal box. Use a camera to aim the laser, not your remaining vision.
And while you may be legally blind, nerve damage your eye is still an issue, as a retinal burn can really fu#k up the muscle coordination between your eyes, potentially causing a lifetime of migrains.
The standard Safety precautions for using one of these fill a pretty thick book.
As some folks have left out a few important details about driving one of these in this thread, you'll probably turn it into a dim blue Led in under 200 nanoseconds, anyways.
Not a toy.
Steve