| 摘要 |
An optical scanning device for scanning an optical record carrier comprising an information layer. Crosstalk cancellation is provided using a phase modulating element (40, 140) for generating a phase profile providing an annular spot shape for a subsidiary beam which is coaxial with the main beam. The phase profile varies with an azimuthal angle measured about the optical axis of the beam portion. Further, a grating element (6, 106) is provided to generate two side beams. Each of the side beams and the subsidiary beam are focused to respective spots on the information layer along with the main beam spot. A radiation detector arrangement (25, 125) is provided for detecting information signals in each of the main beam, the two side beams and the subsidiary beam, and a signal processing arrangement (41, 42, 43, 44, 46, 47, 49) conducts crosstalk cancellation between the respective information signals to generate an output information signal. The invention provides a four-channel crosstalk cancellation arrangement which is capable of providing significantly improved crosstalk canceling performance.
|
