| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens to be used for an optical pickup optical system, which reduces aberration caused by use environment. <P>SOLUTION: The objective lens has difference in level of non-periodical and circular band shape which comprises many stages of structure that generates phase difference of integer multiple of 2π for luminous flux of wavelength λ from a light source in a region corresponding to the number of apertures of any one of both planes as conditions for satisfying following formula (1) to (5): formula (1) 0.845≤ NA ≤0.855, formula (2) ¾Δt¾≤0.025 mm, formula (3) ¾ΔSA¾≤ 0.22λms, formula (4) WFA ≤ (1/14)+ΔSA formula, (5)¾ β¾≤¾0.0046¾. <P>COPYRIGHT: (C)2011,JPO&INPIT |
