A useful optical device to provide continuously variable rotation of polarization of linearly polarized light in a wavelength-independent manner. This device features a cell of twisted nematic liquid crystal sandwiched between an input window and a rotatable output window, both with surfaces prepared so as to orient the nematic liquid crystal molecules. This optical device has different applications such as: variable-angle polarization rotator; using broad band polarizers as an energy attenuator; working in both cases as a wavelength independent and temporal pulse width independent device. The low cost, the very wide field of view, the wavelength and pulse width independence, the high efficiency, and its mechanical simplicity make of this new optical device a very useful and novel invention.
This invention relates to an optical device useful for moderation of infrared, visible and ultraviolet radiation, and in particular to a novel optical device which can rotate the polarization of light by any desired angle, independent of the radiation wavelength, pulse width and incident angle and claims priority based on U.S. Provisional Application Serial No. 60/170,799 filed Dec. 15, 1999.
A non-circular, mechanically variable optical attenuator using a pair of specially constructed polarizing elements with means enabling a gradual transition from un-crossed polarization vector fields to crossed polarization vector fields using a linear motion with respect to one another. The polarizing elements whose polarization axis varies with spatial position on the element have a polarization vector field that is a function of position on the element. Specifically, the two polarizing elements have a defined orientation of polarization axes or vectors on the polarization vector fields that vary with spatial location on the polarizing element such that when aligned light passes, and when the polarization axes are crossed, light is attenuated. The present attenuator has a practical application for dimmable mirrors or windows by providing a variable optical attenuator that is purely mechanical and non-circular in shape. Dimming of the mirror or window is controlled by gradually sliding one such special polarizer with respect to the other.
