US Patent 7471436 Polarizing, photochromic devices and methods of making the same

A security element connected to at least a portion of a substrate, the security element including an at least partial coating having a first state and a second state connected to at least a portion of the substrate, the at least partial coating being adapted to switch from a first state to a second state in response to at least actinic radiation, to revert back to the first state in response to thermal energy, and to linearly polarize at least transmitted radiation in at least one of the first state and the second state.