Optical pickup apparatus

An optical system for use in an optical pickup apparatus for focusing a first light beam and a second light beam, wherein the wavelength of the second light beam is larger than that of the first light beam, the system comprising:

• a first objective lens, including an incident plane and an outgoing plane, which at least one of the incident plane and the outgoing plane has a predetermined flat domain from an optical axis;
• and
• a second objective lens which focuses a light beam transmitted through the predetermined flat domain of the first objective lens on an arbitrary spot on a disk,
• wherein the predetermined flat domain transmits the second light beam only.

An optical pickup apparatus for focusing a first light beam and a second light beam, wherein the wavelength of the second light beam is larger than that of the first light beam, comprising:

• a light source for emitting the first and second light beams;
• a light splitter for transmitting or reflecting the first and second light beams emitted from the light source;
• a collimator lens for making the first and second light beams progressed from the light splitter into parallel light beams;
• a reflecting mirror for reflecting the parallel light beams transmitted through the collimator lens and alternating an optical path thereof;
• and
• first and second objective lenses, in which the first objective lens includes an incident plane and an outgoing plane,
• wherein a flat domain is formed at a designated radius from center on both incident and outgoing planes of the first objective lens,
• wherein one or both flat domains of the incident and outgoing planes are coated, and
• wherein the first objective lens focuses the alternated light beams reflected by the reflecting mirror on an arbitrary spot on a disk.

An optical apparatus for focusing a plurality of light beams, with different wavelengths comprising:

• a first objective lens including at least one of an incident plane flat domain and an outgoing plane flat domain, and including an incident non-flat domain and an outgoing non-flat domain, wherein the at least one of the incident plane flat domain and the outgoing plane flat domain is approximately centered about an optical axis;
• and
• a second objective lens placed downstream from the first objective lens,
• wherein the first and second objective lenses focus the plurality of light beams onto a disk media, and
• wherein at least one of the plurality of the light beams enters the first objective lens through the incident plane flat domain and the at least one of the plurality of the light beams exits the first objective lens through the outgoing plane flat domain.

An optical apparatus, comprising:

• a first objective lens;
• and
• a second objective lens down stream from the first objective lens,
• wherein the first and second objective lenses focus a first light beam and a second light beam onto an optical medium,
• wherein the first light beam is of a first wavelength and the second light beam is of a second wavelength different from the first wavelength,
• wherein a first portion of the first objective lens prohibits transmission of the first light beam and allows transmission of the second light beam,
• wherein a second portion of the first objective lens, different from the first portion of the first objective lens, allows the transmission of the first light beam.