http://img338.imageshack.us/img338/9050/polarizerya6.jpg [Broken] I apologize for my bad sketch. Hi, I need help understanding how this setup changes the polarization of the outgoing beam if the entire setup is rotated. There are 3 mirrors (gold): 2 mirrors are adjacent and set at 30 degrees, and the third mirror is directly centered above the first 2 mirrors. The laser beam strikes the first mirror (left) at the center, then strikes the center of the top mirror, and finally propagates to the third mirror and gets reflected out. The laser beam I'm using to test this home-made polarizer is a basic HeNe laser. Question: How can an incident unpolarized light become polarized outgoing by rotating the entire setup? (All three mirrors are connected to the same aluminum module). I can only see how POLARIZED (s or p) light can work with this setup, but not unpolarized light. Is the laser beam in fact polarized? Thanks.