OBJECTIVE LENS, REPRODUCING DEVICE AND REPRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To read also the CD by one objective lens for the DVD(digital video disk) without adding any peripheral member. SOLUTION: A light beam emitted from a common light source 11 is focused on signal recording surfaces 1a and 2a of the DVD 2 and the CD 1 having different light transmitting layers 1c and 2c in thickness respectively by the common objective lens 8. In this case, since the numerical aperture NA from an optical axis of the objective lens 8 for the DVD 2 is made to fall within a range of 0 to 0.3-0.4, and a correcting lens surface 8a is processed for the purpose of correcting aberration that is generated when the CD 1 is read out by the objective lens for the DVD 2, the CD can also be read out by the objective lens for the DVD.