| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diffractive optical element suitably correcting axial color aberration and the like with respect to a luminous flux having a short wavelength even when a tolerance to a manufacturing error is high and applied to an optical pickup device having compatibility with optical information recording media having protective layer thicknesses different from each other, to provide an objective lens and the optical pickup device using the same, and to provide an optical information recording and reproducing device. <P>SOLUTION: When an effective diameter is De, a diffraction structure within a prescribed height h from an optical axis X is dor-th diffraction, a diffraction structure outside the prescribed height h from the optical axis is dor'-th diffraction and the width of a diffraction circular ring in the case of the dor-th diffraction is Δ in the diffraction structure of the diffractive optical element, the width Δ' of a diffraction circular ring in the case of dor'-th diffraction becomes (dor'/dor)Δ. Δ'>Δ is satisfied when dor'>dor is satisfied, so that the width of the diffraction circular ring can be made wide in the diffraction structure outside the prescribed height h. <P>COPYRIGHT: (C)2009,JPO&INPIT |
