| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device capable of smoothly reducing influence of stray light and also suppressing the deterioration of a detection signal due to shift of an objective lens.SOLUTION: A spectroscopic element H2 has diffraction regions H2a to H2g. Laser beams incident on the diffraction regions H2a to H2f are diffracted in directions Da, Vb, Vc, Dd, Vf, Vg, respectively. A laser beam incident on the diffraction region H2g is diffracted so as not to be incident on a sensor portion of a photo-detector. The diffraction region H2g is configured such that the length y3 thereof in the vertical direction is larger than the length x thereof in the lateral direction. Thus, in a light receiving surface of the photo-detector, a region irradiated with reflection light from a focused recording layer and a region irradiated with reflection light from recording layers other than the focused recording layer are less likely to overlap each other. Accordingly, interference between signal light and stray light becomes difficult to occur, and thereby the deterioration of a detection signal of the sensor portion can be suppressed. |
