| 摘要 |
PURPOSE: To read out optical information of high utilization efficiency from both of different optical recording media by correcting the spherical aberration considered to be necessary for reading out the information from the optical recording media having the different thickness of the substrate by a ray flux splitter. CONSTITUTION: A collimator lens 23 collimates the ray flux corresponding to P polarized light to parallel rays and imparts the refraction different from the refraction of the P polarized light to the ray flux corresponding to S polarized light of the optical path length shorter than the optical path length of the ray flux corresponding to the P polarized light. The ray fluxes passing the lens 23 are, therefore, made incident on an objective lens 24 with the different incident faces of the peripheral edge rays while the optical axes are the same as each other. The spherical aberration is so corrected as to be made nearly zero to the respective incident ray fluxes in the lens 24. Then, the lens 24 focuses the respective ray fluxes in the state that the spherical aberrations are corrected. Then, the reading out of the information of the optical disk is possible if the information recording surface exists within the range where the spherical aberrations are corrected. As the result, the information from the optical recording media having the different thicknesses of the substrates is read out by correcting the spherical aberrations. |
