Two laser source optical pickup with a plano-convex lens to compensate for aberration caused by discs of different thicknesses

摘要

An optical pickup includes a first and second light-emitting elements, a light separating element, and an objective lens. A collimating lens is disposed in the first optical path connecting the first light-emitting element and the light separating element, and an optical element which produces a rotationally symmetrical wavefront aberration is disposed in the second optical path connecting the second light-emitting element and the light separating element. Light is emitted from the first light-emitting element when a thinner disk is used. Light passes through the light separating element and the objective lens to the disk. Light is emitted from the second light-emitting element when a thicker disk is used. Light passes through the light separating element and the objective lens to the disk. In the latter case, the optical element produces aberration to compensate aberration caused by the objective lens so that a small clean spot can be formed.