Abstract: Conventional retroreflection mirrors in the form of right angle prisms are quite sensitive to beam position and beam angle errors. Manufacturing and assembly tolerances are also a cause of concern in conventional devices. Accordingly, the present invention solves these aforementioned problems by providing a retroreflection device comprising: a beam director, preferably in the form of a Wollaston prism; a polarization rotator, preferably in the form of a quarter wave plate; and a flat reflective surface, such as a plane mirror. The device of the present invention is far less sensitive to beam angle alignment and is completely independent of the beam position. The present invention is particularly useful as a beam splitter for directing orthogonally polarized beams of light back along parallel paths in an interleaver apparatus.

Abstract: Conventional retroreflection mirrors in the form of right angle prisms are quite sensitive to beam position and beam angle errors. Manufacturing and assembly tolerances are also a cause of concern in conventional devices. Accordingly, the present invention solves these aforementioned problems by providing a retroreflection device comprising: a beam director, preferably in the form of a Wollaston prism; a polarization rotator, preferably in the form of a quarter wave plate; and a flat reflective surface, such as a plane mirror. The device of the present invention is far less sensitive to beam angle alignment and is completely independent of the beam position. The present invention is particularly useful as a beam splitter for directing orthogonally polarized beams of light back along parallel paths in an interleaver apparatus.