| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a single objective for condensing beams with different wavelengths on different recording surfaces of an optical disk, and provide an optical pickup device using the same. <P>SOLUTION: An objective OBJ uses: a first beam with a wavelength λ1 that is emitted from a first light source LD1 to form a condensing spot on a first information recording surface RL1 of an optical disk OD through a protective layer with thickness t1; and a second beam with λ2 (λ1<λ2) that is emitted from a second light source LD2 to form a condensing spot on a second information recording surface RL2 of the optical disk through a protective layer with thickness t2 (t1≠t2). The objective OBJ satisfies the following formulae: (1) ¾WD1-WD2¾≤0.005 mm; and (2) 40≤νd≤65. In the formulae, WD1 represents distance between the objective and the optical disk in condensing the first beam on the first information recording surface, WD2 represents distance between the objective and the optical disk in condensing the second beam on the second information recording surface, and νd represents the Abbe number to a d line of a material for the objective. <P>COPYRIGHT: (C)2013,JPO&INPIT |
