OPTICAL SCANNING DEVICE

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 non-rotationally-symmetric phase profile in a subsidiary radiation beam. The phase profile varies with an azimuthal angle measured about the optical axis of the beam portion, the phase profile varying such that successively different phases are introduced in at least five locations which are each at successive azimuthal angles (phi1, phi2, phiN) and each at a given radial distance from the optical axis, wherein the phase profile is such that the phases introduced, when taken in modulo 2pi form, successively cycle through 0 to 2pi at least twice, whereby the subsidiary beam spot is provided with an intensity distribution on the information layer which overlaps that of the side-lobe of the main beam spot.