An objective lens for recording andor 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. Methods of making and using such compositions are also disclosed. A nose padding member extends downward from a central portion of the horizontal rod and includes two legs each defining an engaging groove. The magnetic core includes a plurality of divided cores into which the magnetic core is divided in the generatrix direction.