Patent ID: 8385180

Claim:
An optical pickup apparatus comprising: a laser diode; an objective lens made of a synthetic resin, the objective lens configured to focus laser light emitted from the laser diode to a signal recording layer of an optical disc; a collimating lens arranged in an optical path between the laser diode and the objective lens, wherein: the collimating lens has a radius of curvature greater than a radius of curvature of the objective lens; and an annular diffraction grating is formed on a surface of the collimating lens farthest from the objective lens, the annular diffraction grating configured to correct chromatic aberration that occurs in response to a change in a refractive index of the objective lens with a change in wavelength of the laser light, and a mirror arranged in the optical path between the collimating lens and the objective lens, the mirror reflecting the laser light passed through the collimating lens in a direction of the objective lens; wherein: the collimating lens is moved in an optical axis direction of the laser light to correct for spherical aberration occurring in response to a change in temperature when performing a recording operation for the optical disc, and the collimating lens corrects, due to the annular diffraction grating, chromatic aberration occurring when switching from the recording operation to a reproducing operation for the optical disc.