| 摘要 |
An optical device (29) for rotating the polarization of a linearly polarized, broadband input beam of light (3) comprises prism means (30, 37, 43). The input beam is incident normal to a first face (31) and exits normal to a second face (47) of the prism means. The prism means comprises a light transmitting material having a plurality of totally internally reflecting surfaces (32,33,34) and one or more interfaces, the totally internally reflecting surfaces are arranged such that the polarization of the exit beam is rotated by 90° relative to the input beam, each interface comprises a pair of parallel surfaces (35, 39) separated by a gap (36), the parallel surfaces are arranged substantially to satisfy the Brewster condition such that surface reflection losses are minimized and the input and exit beams are substantially collinear.
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