| 摘要 |
PURPOSE:To take out the reflection light from an optical disk by an exclusive light receiving element by separating it in the signal detection lights for information, focusing and tracking by equipping a specified detector lens and hepta- sected optical detector. CONSTITUTION:A laser diode 11, collimeter lens 12, polarized beam splitter 13, 1/4 wavelength plate 14, objective lens 15, detector lens 18 and an optical detector 20 are provided. The detector lens 18 makes a circular plain convex lens as the base, the spherical face 18a of one face is left as it is, the plane side of the opposite side is left just as the plane orthogonal with the optical axis at the square zone 18b including the optical axial center and the circumference part thereof is made the slope 18c, 18d and 18e, 18f opposed each other. On the other hand, the optical detector 20 is taken as the hepta-sected optical detector having a pair of light receiving elements 20a, 20b arranged at both sides, the center light receiving element 20c, the light receiving elements 20d, 20e and 20f, 20g arranged by approaching respectively on one plane. The signal detection light for information, for tracking control and focus control can thus be taken out by separating it. |
