Mechanism for moving a lens along the optical axis

摘要

A lens driving apparatus for detecting a focus state comprises an objective lens comprising a plurality of lens units (1) having an optical axis, and a member rotating about a predetermined axis of rotation to finely move a lens unit of said plurality of lens units (1) of said objective lens in a direction of the optical axis, wherein said member has a peripheral surface such that a distance from the predetermined axis of rotation to the peripheral surface is gradually changed, wherein said lens unit is moved forwardly or backwardly in a direction of the optical axis of said objective lens according to rotation of the peripheral surface. <IMAGE> <IMAGE>