| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical element for an optical pickup device which is inexpensive while in which appropriate opening restriction can be performed and an optical pickup device using the same. <P>SOLUTION: A luminous flux OL1 passed through at the most outside of a first region reaches an edge of a spot SP converged on an information recording plane through an objective lens being not illustrated. On the other hand, since luminous flux OL2 passed through at the most inside of a second region is tilted by an angle γ for the luminous flux OL1, when it is converged on the information recording plane through the objective lens being not illustrated, it reaches a position separated from the center of the spot SP by distance δ and becomes flare light. A photodetector being not illustrated can receives reflected light in the spot SP, but since light that reaches a position separated from the center of the spot SP by distance δ exceeds a light receiving range, the light cannot be received. Thus, by providing radiation shaped diffraction structure, the opening restriction function can be displayed in the same way as the case annular diffraction structure is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT |
