| 摘要 |
A compound polarization beam splitter ( 33 ) for use with a reflective, polarization-modulating, imaging device ( 10 ), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism ( 20 ); (b) an output prism ( 30 ), and (c) a polarizer ( 13 ), which is located between the two prisms ( 20,30 ) and which may be a wire grid polarizer ( 13 a) or a multi-layer reflective polarizer ( 13 b). Polarized illumination light ( 11 ) enters the input prism ( 20 ) through a first surface ( 21 ) and undergoes total internal reflection at a second surface ( 22 ) before being reflected from the polarizer ( 13 ) and polarization-modulated at the imaging device ( 10 ). The polarizer's tilt angle (beta) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens ( 74 ).
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