| 摘要 |
PURPOSE:To improve the S/N of a reproducing signal and to attain miniaturization and light weight by utilizing the fact that the diffraction effect of a concave diffraction grating is provided with deflection dependency, and arranging the convergence part of the concave diffraction grating and every constitutional part on a Rowland circle. CONSTITUTION:Monochromatic light having linear polarizing characteristic from a monochromatic light source 21 is guided to the concave diffraction grating 23, and is image-formed on the recording plane of an optical disk D as a light source image with the grating 23. Since radiant light from the light source 21 is P-polarized light against the grating 23, an S-polarized light component is generated by the rotation of a polarizing plane by a Kerr effect. Then, the S-polarized light component goes to the reproducing signal corresponding to recording information. Thus, when reflected light including the P- and S-polarized light components is guided to the grating 23, the S-polarized light component is reflected as nth-order diffracted light with the grating, and is guided to a reproducing detector 24. The P-polarized light component is reflected as mth-order diffracted light with the grating 23, and is guided to an error signal detector 25. And since the focal points and the recording planes of the detector 24 and 25 are arranged on the Rowland circle C of the grating 23, the light can be image-formed on a focal point plane. |
