| 摘要 |
<p>A large-area collimated beam (1) of radiation is formed by re-directing a beam of small projected area off one or two orthogonal surfaces (11, 12) which are faceted or have a non-specular reflection angle and which spatially distribute the incoming (1) beam across their surface area. Preferably there are two expansion stages, one for each dimension. If the input beam (1) is linearly polarised then the output beam will also be polarised. The polarisation will undergo a rotation through 90 degrees. The beam expander is compact and suitable for use in liquid-crystal flat-panel displays.</p> |
