| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, in an optical pickup device being made so as to deal with the recording media in which the thicknesses to the signal surfaces of transparent substrates are different, that the spherical aberration arises in an optical spot converging on a low signal recording density recording medium because the optical characteristics of an optical system including an objective lens is set with the priority of the recording medium that has a high recording signal density. SOLUTION: The optical characteristics are set so that the objective lens 7 is made so as to be suitable for the recording medium whose transparent substrate is thin. A spherical aberration component, which compensates the spherical aberration which arises in the recording medium whose transparent substrate is thick, is added to a divergent lens 4 disposed in front of a first laser element 1. Thus, another optical element is not necessarily installed for compensating the spherical aberration which arises in the recording medium whose transparent substrate is thick. The spherical aberration component compensating the spherical aberration is made so as not to badly influence the optical system dealing with the recording medium whose transparent substrate is thin. |
