US Patent 7619804 Electrochromic polarizer

The polarization of a beam of radiation can be changed by passing the beam through an electrochromic device (ECD) and applying voltages to the ECD to selectively change the absorption of components of the beam and to change its polarization. This method can operate over a wide spectral region that may extend from 200 nm to 30 μm. In addition, the polarizer can be configured to be tuned by moving the polarizer transversely with respect to a beam of radiation that is characterized by a selected wavelength. In this case either or both of the composition and thickness of the polarizer may vary along the direction of motion in a controlled fashion.