Abstract: The present invention provides an objective lens system for optical recording type disks, comprising from a light source side to a disk side; a first lens element having a positive refractive power, said first lens element having at least an aspherical surface; a second lens element having a positive refractive power; and wherein the objective lens system fulfills the following condition:-1/2<.beta.<-1/8wherein .beta. represents the magnification of the whole lens system.

Abstract: An objective lens system for use in a device for optically reading digital data on an optical disk is constituted by a single objective lens without use of a collimator lens element. A light source side aspherical surface of the objective lens element has a positive refractive power and a disk side surface thereof has a positive refractive power, too. The objective lens system is used with the projecting magnification .beta. which falls within the range -1/2<.beta.<-1/8.The objective lens system fulfills the following condition:0.9.ltoreq.(N.sub.1 -1)r.sub.1 /f.ltoreq.3.91.4.ltoreq.d.sub.1 r.sub.1 /f.sup.2 .ltoreq.4.01.4.ltoreq.d.sub.1.sup.2 /f.sup.2 (N.sub.1 -1).ltoreq.4.0wherein,f represents the focal length of the single lens element;r.sub.1 represents the paraxial radius of curvature of the light source side surface of the single lens component;N.sub.1 represents the refractive index of the single lens element; andd.sub.1 represents the axial thickness of the single lens element.

Abstract: The present invention provides an objective lens system specifically designed for optically recording and reading digital data on an optical disc. The lens system includes three lenses, with one of the lenses having an aspherical surface. The first lens element can have a positive power with a spherical surface on its light source side. The second lens element can have a positive refractive power while a third lens element can also have a positive refractive power. The lens system can fulfill the following conditions.-0.3<f/r.sub.1 <0.25.vertline.r.sub.4 /r.sub.3 .vertline.<0.5wherein:f represents the focal length of the whole lens system;r.sub.1 represents the paraxial radius of curvature of the light source side aspherical surface of the first lens element;r.sub.3 represents the radius of curvature of the light source side surface of the second lens element; andr.sub.4 represents the radius of curvature of the disk side surface of the second lens element.