| 摘要 |
<p>Provided is a single objective lens that sufficiently reduces aberration when parallel rays are input to an optical disk, no matter what optical disk said parallel rays are input to, said optical disk being a BD, DVD or CD. In a three-wavelength common area (103) of the objective lens (100), first to third orbicular zone phase shift structures (112-114) are formed integratedly with a lens surface optimized to a transparent medium layer of thickness (t4). In a BD/DVD common area (104), a fourth orbicular zone phase shift structure (117) is formed integratedly with a lens surface optimized to a transparent medium layer of thickness (t5). A dedicated BD area (105) has an aspherical lens shape optimized to a transparent medium layer of thickness (t1). The orbicular zone phase shift structures: correct wave surface aberration that has defocus as a main component thereof and is mutually similar among the BD, DVD and CD; but as a result of compositing, are capable of correcting wave surface aberration that is not mutually similar among the BD, DVD and CD.</p> |
