If you have 3 perfect polarizing films and you place them on top of the other, with each successive film oriented +45 degrees from the one before it (first and last oriented perpendicular to each other and middle polarizer at 45 degrees between them). If one shines a light on this polarizer stack with an intensity of 1 watt, what is the intensity of the light on the other side of the three polarizer stack? Now when I tried to figure this out I assume that the light is collimated and that the films are perfect polarizer. But I got stuck on the actually equation... Anyone out there knows how to solve this?