Optical disc scanning arrangement - uses half wavelength plate rotated to reduce unwanted polarisation effects

摘要

The equipment comprises a first laser (1), focusing lenses (2,9, 11,15) a grating (3), a light splitting piston (4), a mirror (5), polarising splitters (6,12), lens (7), a recording medium (8), a second laser (10), a two-part photodetector (13), a photodetector (14), a cylindrical lens (16), a quad-photo detectors (17) with quadrants (A,B,C,D) and photo detectors (E,F), a half-wavelength disc (24), differential amplifiers (22,23), a low filter (19) and a multipler (18). A half-wavelength disc (24) is inserted in the light path between the laser (1) and the recording medium (8), and is rotated to put the E-vector of the laser light into the desired position relative to the recorded data. USE/ADVANTAGE - Optical discs players. Reduces unwanted polarisation effects.