| 摘要 |
<p>An optical pickup device and an information recording and reproducing device are provided for making it possible to carry out proper information recording and/or reproducing for an optical information recording medium with multiple-layer information recording surfaces. With respect to a direction perpendicular to an optical axis of an objective lens (OBJ) provided with a compatible diffraction structure, multiple-layer information recording surfaces (LY1, LY2) of an optical recording medium as shown by solid lines are inclined, so that a light bundle is made to be incident from a light source to an objective lens along the optical axis. The n-th diffraction light generated from the diffraction structure is reflected from the information recording surface (LY1), returns to a direction inclined with respect to the objective lens (OBJ) and is detected by a light detector (PDy). On the other hand, when the m-th diffraction light, (m ? n), is collected on the information recording surface (LY2), the diffraction light returns to a direction inclined with respect to the optical axis of the objective lens (OBJ) but two reflecting light components (R1, R2) are shifted to become in parallel. Thus, if the light detector (PDy) is set at a position where only the reflecting light (R1) can be detected, there is a less risk that the reflecting light (R2) is detected in error, so that information recording and/or reproducing can be carried out properly.</p> |
