| 摘要 |
<p>An objective lens that is used in an optical pickup device according to the present invention comprises a first light source that emits a first luminous flux of a first wavelength (lambda1) (390nm<=lambda1<=420nm), a second light source that emits a second luminous flux of a second wavelength (lambda2) (630nm<=lambda2<=670nm), and a third light source that emits a third luminous flux of a third wavelength (lambda3) (760nm<=lambda3<=820nm), performs recording and/or reproduction of information of a CD which has a protective substrate with a thickness of (t1) using the first luminous flux, performs recording and/or reproduction of information of a DVD which has a protective substrate with a thickness of (t2) (t1<t2) using the second luminous flux, performs recording and/or reproduction of information of a CD which has a protective substrate with a thickness of (t3) (t2<t3) using the third luminous flux, and satisfies the following formula: 1.9<=LTCM3(lambda1)/LTCM3(lambda2)<=10.0.</p> |
