| 摘要 |
PROBLEM TO BE SOLVED: To suppress the degradation of the high frequency component of a reproduced signal by effectively inverting the signal polarity of an information bit string by only one pair of areas having convex shaped boundaries symmetrically to the center of a luminous flux at both sides of a direction orthogonally crossing the information bit string direction of an optical recording medium. SOLUTION: A light beam reflected and incident in a reproduced signal detecting system is rotated in the polarization direction by 45 degrees by a λ/2 plate 25 to be made incident on a perforated half-wave plate 10. Two holes of the plate 10 are opened at both sides of a direction orthogonally crossing an information bit string. Moreover, a servo signal is fed back to a two-dimensional actuator 20 on which an objective lens 7 is mounted to control a light spot so as to follow up the information bit string. Here, crosstalk of adjacent tracks is reduced by inserting the perforated λ/2 plate 10 and also when a closest bit frequency is smaller than λ/NA, the closest signal amplitude is adjusted so as not to be reduced by a mask insertion with respect to a wavelength λ and the numerical aperture NA of the objective lens. |
