Yoshisato FUJIOKA

Fujioka Research Laboratory, Mahk Co., Ltd., 1-38-6, Egota, Nakano-ku, Tokyo, 165-0022 Japan

(Received July 26, 1996; Accepted February 3, 1998)

As the thickness of a disk base is varied, the variation of spherical aberration becomes remarkable. An objective lens system with compensating lenses on the light source side is designed. By moving the compensating lenses along the optical axis backward or forward, the spherical aberration caused by the variation in thickness of the disk base is corrected.

Key words : objective lens, variable thickness, disk, base, compact disk, digital video disk