Patent ID: 8363533

Claim:
An optical pickup apparatus comprising: an objective lens having a numeric aperture, and including an incident face; an antireflection coating formed on the incident face of the objective lens, the antireflection coating being a single layer antireflection coating, or a multi-layer antireflection coating comprising a first layer formed on a second layer; and a collimating lens configured to convert laser light emitted from a laser diode into parallel light, cause the parallel light to be made incident on the incident face through the antireflection coating of the objective lens, and be displaced in a direction of an optical path so as to correct spherical aberration generated due to a difference in thickness of a protective layer of an optical disc, wherein, as a result of the thickness of the antireflection coating: a transmittance of laser light that enters the objective lens through the incident face is set at a first predetermined transmittance value, when the numeric aperture of the objective lens is between zero and a first predetermined numeric aperture value; a transmittance of laser light that enters the objective lens through the incident face is set to correlate linearly with the numeric aperture when the numeric aperture of the objective lens is between the first predetermined numeric aperture value and a second predetermined numeric aperture value; and a transmittance of laser light that enters the objective lens through the incident face is set at a second predetermined transmittance value, when the numeric aperture of the objective lens is between the second predetermined numeric aperture value and a third predetermined numeric aperture value, or is equal to the third predetermined numeric aperture value.