Patent ID: 8379188

Claim:
An optical system having an optical axis, the optical system comprising: a first polarization manipulator, comprising: a first subelement having a non-planar, optically effective surface, the first subelement configured so that the first subelement changes a polarization state of light passing through the first subelement, a maximum effective retardation introduced by the first subelement along the optical axis being less than a quarter of a working wavelength of the optical system; and a second subelement, the first subelement and the second subelement having mutually facing non-planar surfaces that are mutually complementary; and a position manipulator configured to manipulate a relative position of the first and second subelements with respect to each other; wherein: during use of the optical system, the light follows a beam path through the optical system; and the first and second subelements are arranged consecutively in the beam path.