Objective lens system for optical reading device

摘要

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