| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup device which appropriately performs recording and/or reproducing of information for three kinds of disks having different recording density, and achieves simplified constitution and cost reduction, and to provide an objective lens. <P>SOLUTION: A tracking property is improved by making divergence luminous flux incident on the objective lens OBJ during use of a DVD, further, working distance of 0.4 mm or more can be secured by making infinitive parallel luminous flux incident on the objective lens OBJ during use of a CD, further, variation in diffraction efficiency caused by variation in wavelength of a power source can be suppressed to small by setting diffraction order so that at least one out of M, N, O is positive, and at least one out of M, N, O is negative. <P>COPYRIGHT: (C)2009,JPO&INPIT |
