| 摘要 |
PURPOSE:To form a main spot of a diffraction limit or below and make laser light stably follow a track without loss accompanying the situation in which three beams are used. CONSTITUTION:The laser light emitted by a laser light source 1 is guided to a collimator lens 2, a super high resolution modulator 3, a polarization beam splitter 4, and a lambda/4 plate 5 to form the main spot and side spots 8a and 8b on a recording medium 7 through an objective 6. This super high resolution modulator 3 is formed in a repetitive pattern of transmission areas and light shield areas composed of diffraction gratings, and consequently a track error signal is detected by forming the main spot 8 of the diffraction limit or below from the transmitted light and also using the side spots of low sidelobe intensity formed from diffracted light. |
