Patent ID: 8179768

Claim:
An optical system for optical pickup, the optical system being used in an optical pickup device that performs at least one of reading, writing, and erasing of information on a recording layer within an optical recording medium, the optical system comprising: a wavefront conversion optical system that includes at least one lens element and converts a wavefront of a light beam emitted from an external light source; and an objective optical system that converges a light beam emitted from the wavefront conversion optical system and forms a spot on the recording layer, wherein the wavefront conversion optical system adjusts a focal point of the spot on the recording layer and compensates a spherical aberration of the spot in a state where an interval between a surface of the optical recording medium and a lens element of the objective optical system that is nearest to the surface is maintained constant, by changing an interval in an optical axis direction between the light source and the lens element of the wavefront conversion optical system.