| 摘要 |
PROBLEM TO BE SOLVED: To detect desired information by shielding the part of a first laser beam reflected from the surface of an optical disc passing through a region separated by a specified distance radially from the center of an objective lens thereby shielding the part of the reflected light having adverse effect on a reproduced signal or a focus error signal. SOLUTION: The 0 order diffracted light L1A and the 1 order diffracted lights L1B, L1C of a laser beam L1 are reflected from the reflective surface of a CD 14B and the first through third reflected lights L2A-L2C enter into an objective lens 24. A lens holder 30 is provided with an annular light shielding part shielding the light for a partial region on one side of the objective lens 24 facing a DVD 14A or the CD 14B. According to the arrangement, such part of the first reflected light L2A entering into the objective lens 24 as having a worst effect on a reproduced signal is shielded by the light shielding part of the lens holder 30 and the remaining unshielded first through third reflected lights enter into a multilens 25. |
