| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device which controls the positions of an objective lens and an optical disk without error by eliminating a noise due to a lens characteristic in an optical pickup device in which an objective lens which is a bifocal lens is used. SOLUTION: In the optical pickup device 1 in which the objective lens 11 which is a bifocal lens is used, a dichroic filter 9, which limits the aperture of a laser beam 4 with respect to the objective lens 11 which aperture is likely to give an influence of the noise to a focal point error signal(FES), is provided between a semiconductor laser 3 and the objective lens 11, so that the light beam is not made incident to the outer region of the objective lens 11 and the noise due to the lens characteristic is eliminated, thus the optical pickup device 1 which controls the positions of an objective lens 11 and an optical disk 12 without error is provided. |
