- Polaroid computer screen cover
- 2 square (approx 6") linear polarizers
- Place the large circular polarizer on the OHP, "terminal side" upward, and focus the OHP.
- Light coming through the screen is circularly polarized. Slide a linear polarizer half way under the circular polarizer. Place 2nd linear polarizer on top of the screen polaroid and aligned with the first linear polarizer.
- Turn the top linear polarizer. Note that the light can be blocked by the linear polarizers, but not as it comes through the circular polarizer.