| 摘要 |
The illumination system (21) includes two radiation sources (23, 25) and an optical system for concentrating the radiation into beams, a common polarizing system (11) for splitting the beams (bI, bII) into linearly polarized sub-beams, and at least one polarization-rotating element (35). The polarizing system includes at least one optically transparent plate (11) having a refractive index n0 and a first face and a second face. At least one of these faces is provided with an optically thin layer having a refractive index n1 which is larger than n0. The light path of the sub-beams whose directions of polarizations are not to be converted incorporates a reflector (41, 43) for reflecting the sub-beams into the same direction of propagation as that of the other sub-beams. The chief ray of these beams and the normal on the plate (11) enclose an angle which is substantially equal to the Brewster angle which holds for the interface between the optically thin layer and a medium surrounding the polarizing element (11).
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