| 摘要 |
PROBLEM TO BE SOLVED: To improve read signal quality while increasing its linear recording density. SOLUTION: An optical recording medium 1 in which the distance from a light incident surface to an information recording layer is less than 100μm is irradiated with a laser beam through an objective lens and information stored in the information recording layer is read by means of a PRML identification method. At this time, the constraint length n in the PRML identification method is set to an integer which satisfies 0.5x(λ/NA)/(LV/f)-1<n<0.5x(λ/NA)/(LV/f)+1, whereinλrepresents the wavelength of the laser beam, NA represents the numerical aperture of the objective lens, LV represents the linear velocity of the optical recording medium when recording, and f represents a channel bit frequency when recording. COPYRIGHT: (C)2009,JPO&INPIT
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