Optical disk apparatus for accessing optical disks with different substrate thicknesses

An optical disk apparatus comprising:

• a laser generator for radiating laser rays for reading information from and writing information to optical disks with different substrate thicknesses, said laser generator including a first laser source and a second laser source whose axes are at right angles to each other;
• an objective lens for focusing the laser rays from the laser generator and forming a laser spot on a recording layer of the optical disk;
• at least one photo detector for receiving reflective light from the optical disk and for outputting a reproducing signal and servo signals;
• a beam splitter located in an optical path between the first laser source and the second laser source;
• and,
• at least one coupling lens located either in an optical path between the beam splitter and the first laser source, or in an optical path between the beam splitter and the second laser source, the coupling lens allowing the objective lens to focus on optical disks of different substrate thickness without causing a spherical surface aberration,
• wherein the lengths of the optical paths from the first laser source and the second laser source to the beam splitter are adjusted, so that the objective lens can be focused on a recording layer of the optical disk without causing a spherical surface aberration;
• and,
• wherein the at least one photo detector further comprises:
• a first photo detector element for receiving a laser ray radiated from the first laser source and reflected from the optical disk;
• a second photo detector element for receiving a laser ray radiated from the second laser source and reflected from the optical disk;
• and,
• a judging control circuit for judging substrate thickness of the optical disk based on signals from the first photo detector element and the second photo detector element, and for connecting either the first photo detector or the second photo detector with a power source in accordance with an output from said judging control circuit.

An optical disk apparatus for reading information from and writing information to optical disks with different substrate thicknesses, comprising:

• a first photo detector element for receiving a laser ray radiated from a first laser source and reflected from an optical disk;
• a second photo detector element for receiving a laser ray radiated from a second laser source and reflected from the optical disk;
• and,
• a judging control circuit for judging substrate thickness of the optical disk based on signals from the first photo detector element and the second photo detector element, and for connecting either the first photo detector or the second photo detector with a power source in accordance with an output from said judging control circuit.

An optical disk apparatus for reading information from and writing information to optical disks with different substrate thicknesses, comprising:

• a first photo detector element for receiving a laser ray radiated from a first laser source and reflected from an optical disk;
• a second photo detector element for receiving a laser ray radiated from a second laser source and reflected from the optical disk;
• and,
• a judging control circuit for judging substrate thickness of the optical disk based on signals from the first photo detector element and the second photo detector element, and for connecting either the first photo detector or the second photo detector with a power source in accordance with an output from said judging control circuit;
• wherein the lengths of the optical paths from the first laser source and the second laser source to a beam splitter are adjusted so that an objective lens can be focused on a recording layer of the optical disk without causing a spherical surface aberration.

A method of accessing a recording layer of an optical disk comprising the steps of:

• providing first and second laser sources located in first and second perpendicular optical paths;
• providing a beam splitter located at the intersection of the first and second optical paths;
• providing at least one coupling lens in either the first or second optical path which reduces a spherical surface aberration;
• providing an objective lens which focuses a laser ray emitted from said beam splitter on a recording layer of an optical disk;
• providing a first photo detector element for receiving a laser ray radiated from the first laser source and reflected from the optical disk;
• providing a second photo detector element for receiving a laser ray radiated from the second laser source and reflected from the optical disk;
• providing a judging control circuit which judges a substrate thickness of the optical disk based on signals from the first photo detector element and the second photo detector element, and which connects either the first photo detector or the second photo detector with a power source in accordance with an output from said judging control circuit;
• and,
• reading or writing information to the recording layer of the optical disk through the focused laser ray.

A method of accessing a recording layer of an optical disk comprising the steps of:

• providing a first photo detector element for receiving a laser ray radiated from a first laser source and reflected from the optical disk;
• providing a second photo detector element for receiving a laser ray radiated from a second laser source and reflected from the optical disk;
• providing a judging control circuit which judges a substrate thickness of the optical disk based on signals from the first photo detector element and the second photo detector element, and which connects either the first photo detector or the second photo detector with a power source in accordance with an output from said judging control circuit;
• and,
• reading or writing information to the recording layer of the optical disk through a focused laser ray.