| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device capable of performing accurate focus control without generating any offset in the curve of a focus error signal(FES) even when a multilayer optical disk having a small distance between recording layers is used, and without generating any disturbances in the FES curve even when an assembling error occurs. SOLUTION: A light from a semiconductor laser 1 is converged on an optical disk 5 by an objective lens 4, and its returning light is guided to a photodetector 7 by a 3-division hologram element 2. The photodetector 7 includes auxiliary light receiving areas 7g, 7h, 7I and 7j for focus error signal correction, which are provided only in two-divided main light receiving areas 7a and 7b for focus error signal FES detection and both sides of outer sides of its dividing line direction. The output signals of the light receiving areas 7a, 7b, 7g, 7h, 7I and 7j are respectively set as Sa, Sb, Sg, Sh, Si and Sj, a focus error signal FES is calculated by (Sa+Sh+Sj)-(Sb+Sg+Si), and an FES curve outside a pulling-in range (in a state of defocus) is improved. |
