| 摘要 |
PURPOSE: To enable a constant track follow-up by forming the main spot of not more than a diffraction limit and side spots in which side lobes are not generated by using an area constituted of a diffraction grating as an area making the light strength of a super-high resolution modulator reduce. CONSTITUTION: Laser light emitted from a laser light source 1 is guided to a collimating lens 2, a super-high resolution modulator 3, a polarizing beam splitter 4, a 1/4 frequency plate 5 to form a main spot 8 and side spots 8a, 8b in which side lobes are not generated on a recording medium 7 by an objective lens 6. The recording, the reproducing and the erasing of the recording medium 7 are performed with the main spot 8 formed from the o-th order diffracted light of the super-high resolution modulator 3 and being not more than the diffraction limit and a track error signal is detected with side spots 8a, 8b formed from the 1st order diffracted lights of the modulator. |
