| 摘要 |
PURPOSE:To detect a stable far field tracking error signal and a a highly sensitive focus error signal by obtaining a polarizing prism by combining a rectangular prism and a flat place, detecting incident beams, and emitting two polarized beams approximately in the same direction. CONSTITUTION:The light beams reflected by a disk pass through an objective lens 6, they are reflected by a first polarizing prism 5, and the polarization direction is rotated in the 45 deg. direction by a 1/2 waveform plate 8. Next the beams are separated into a P polarized component and an S polarized component by a second polarizing prism 10. That is, the S polarized beams are reflected along an AA' axis, and the P polarized beams are reflected along a BB' axis. Further the beams are received by a bisected photo-detector, and by driving the objective lens 6 with the output of the bisected photodetector, tracking servo is executed. Thus the stable far field tracking error signal and the highly sensitive focus error signal can be detected by the one-chip photodetector. |
