Patent ID: 7916392
Filing Date: 2011-03-29
Classification: G02B,G03B,H04N

Abstract:
1. A polarization control system comprising: a polarizing beam splitter having a polarization separating layer to split incident light depending on a polarizing direction and transmit or reflect said light; a reflective type liquid crystal element having a reflective surface to reflect said light from said polarizing beam splitter back to said polarizing beam splitter, and controlling a polarizing direction of said light before and after the reflection of said light by said reflective surface; a first birefringent element disposed between said polarization separating layer of said polarizing beam splitter and said reflective surface of said reflective type liquid crystal element, so that a surface of said first birefringent element is substantially parallel to said reflective surface, and having a slow axis on a plane parallel to said reflective surface; and a second birefringent element disposed between said polarization separating layer of said polarizing beam splitter and said reflective surface of said reflective type liquid crystal element in such a manner that said second birefringent element has an index ellipsoid inclined with respect to a plane parallel to said reflective surface, and said index ellipsoid has a symmetrical plane perpendicular to said reflective surface, and a direction of a principal refractive index on said symmetrical plane is parallel to said slow axis of said first birefringent element, when orthogonally projected on said reflective surface, wherein light traveling vertically to said reflective surface of said reflective type liquid crystal element has a total phase difference of substantially λ/4 by passing through said first and second birefringent elements, where λ designates a wavelength of light.