I have a strong green laser, about 200 mw. I discovered this a long time ago and have wondered why it does this ever since... I shine my laser at a mirror. It bounces back, with a brighter beam. That's not what confuses me. What confuses me is when I try to aim the bounceback beam to perfectly intersect with my current beam, I get this CRAZY pattern on the wall right behind my hands: Kind of like this, but the waves get closer and closer together the further from the center. I am so confused and confounded by this. Can someone explain the physics behind this?