| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk made higher in density by more than the reduced component of a beam spot as compared with a present DVD by the optimum allocation of the higher density component achieved by employing a PRMIL system in a track density direction and a line density direction. <P>SOLUTION: Information is recorded on the optical disk at the track density TP (μm/track) and line density BP (μm/bit) by using a modulation code of d constraint D and encoding efficiency R. The optical disk reproduces the information with an optical system including a light source for reproduction of a wavelength λ (μm) and an objective lens with a numerical aperture NA and a reproduction signal processing system. The optical disk satisfying the conditions TP>(λ/(2NA)), BP>ä1/(2(D+1)R)}x(λ/(2NA)), 0.361≤(BP/TP) is constituted. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
