| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical pickup lens assuring the state where wave aberration is reduced in a numerical aperture of a high range of an upper limit with respect to a plurality of kinds of optical disks varying in using wavelength. <P>SOLUTION: The optical pickup lens is a lens for three wavelength interchanging for performing recording and reproducing of information to a medium having substrates of thicknesses t1, t2, t3 (t1<t2<t2) with light sources of wavelengths λ1, λ2, λ3 (λ1<λ2<λ3). In the case where the recording and reproducing are performed to the medium having the thickness t1 with the light source of the wavelength λ1, the lens is used in an effective numerical aperture of ≥0.8. In the case where the recording and reproducing are performed to the medium having the thickness t3 with the light source of the wavelength λ3, the lens is used in the effective numerical aperture of ≤0.6. At this time, -0.57<r1/t2<-0.45 is satisfied when the radius of curvature of an incident surface on which the light from a light source is made incident is defined as r1, and the radius of curvature of an exit surface as r2. <P>COPYRIGHT: (C)2008,JPO&INPIT |
