| 摘要 |
A polarizing beamsplitter device uses as a beamsplitter a surface relief transmission grating (26) formed so as to have a high diffraction efficiency for S component light and a high transmittance for P component light. In one embodiment relating to a laser read/write system, the grating is used in conjunction with a wave retardation device (28). In this embodiment, light (22) from a laser (20) is incident at about 45 DEG onto the grating (26). The diffracted S component, which leaves the beam-splitter perpendicularly to the incident beam, passes through a lambda /4 wave retardation plate (28) and is focussed by lens (30) onto a video disc (24). Reflected light passes back through the lens and the wave retardation plate, emerging from the plate (28) as a P polarized beam. This beam passes straight through the grating (26) to fall on a detector (32). |
