An objective lens for recording and/or reproducing information of an optical
information
recording medium, comprises a first lens group having a positive refractive power
and a second lens group having a positive refractive power. The first lens group
and the second lens group are arranged in this order from a light source side.
The objective lens is a finite conjugate type to converge a divergent light flux
from a light source onto an information recording plane of the optical information
recording medium and satisfies the following formula:
where NA is an image-side numerical aperture necessary for conducting recording
and/or reproducing information of the optical information recording medium.
