OBJECTIVE LENS, OPTICAL HEAD, AND OPTICAL PICKUP DEVICE

摘要

In an objective lens (2), a first lens (21) is meniscus lens having a negative refractive power and having a concave surface facing a semiconductor laser (3) as a light source. Thus, it is possible to reduce the Petzval sum and reduce the image plane curvature. A second lens (22) is a biconvex lens. A third lens (23) is a meniscus lens having a positive refractive power and having a concave surface facing an optical disc (6). Thus, it is possible to obtain a long working distance. With the objective lens (2) having the aforementioned configuration, it is possible to obtain a high NA while effectively suppressing generation of aberrations, thereby performing a highly accurate optical recording and/or reproduction with a high density.