Optical pickup apparatus

An optical pickup apparatus capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium, the optical pickup apparatus comprising:

• an optical unit for projecting a plurality of lights of different wavelengths, the lights including a celadon light, toward a recording medium and receiving the lights reflected from the recording medium to thereby detect an information signal and an error signal;
• and
• a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applicable for at least three lights having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums;
• wherein the low-density recording medium comprises the DVD and a compact disc (CD);
• and
• wherein the optical unit comprises:
• a first light source for projecting the celadon light for the high-density recording medium;
• a 2-wavelength light source module for projecting an infrared light for the CD and the red light for the DVD and receiving the lights being reflected to thereby detect a signal;
• a first light detector for receiving the light projected by the first light source and reflected from the recording medium to thereby detect a signal;
• a first optical path converter for changing a path of the light projected by the first light source;
• and
• a second optical path converter for changing a path of the light projected by the 2-wavelength light source module;
• wherein the first optical path converter comprises:
• a polarization beam splitter for reflecting or transmitting an incident light according to polarization component of the incident light;
• and
• a wavelength plate for changing the polarization component of the light projected by the first light source and reflected from the recording medium;
• wherein the second optical path converter comprises a non-polarization beam splitter between the wavelength plate and the polarization beam splitter.

An optical pickup apparatus capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium, the optical pickup apparatus comprising:

• an optical unit for projecting a plurality of lights of different wavelengths, the lights including a celadon light, toward a recording medium and receiving the lights reflected from the recording medium to thereby detect an information signal and an error signal;
• and
• a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applicable for at least three lights having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums;
• wherein the low-density recording medium comprises the DVD and a compact disc (CD);
• and
• wherein the optical unit comprises:
• a first light source for projecting the celadon light for the high-density recording medium;
• a 2-wavelength light source module for projecting an infrared light for the CD and the red light for the DVD and receiving the lights being reflected to thereby detect a signal;
• a first light detector for receiving the light projected by the first light source and reflected from the recording medium to thereby detect a signal;
• a first optical path converter for changing a path of the light projected by the first light source;
• and
• a second optical path converter for changing a path of the light projected by the 2-wavelength light source module;
• wherein the second optical path converter is disposed on a path of the light projected by the first light source;
• wherein the second optical path converter comprises the non-polarization beam splitter which reflects or transmits the incident light according to the wavelength of the incident light;
• and
• wherein the non-polarization beam splitter substantially transmits the light having wavelength equal to or greater than 650 nm and reflects the light having wavelength smaller than 650 nm.

An optical pickup apparatus capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium, the optical pickup apparatus comprising:

• an optical unit for projecting a plurality of lights of different wavelengths, the lights including a celadon light, toward a recording medium and receiving the lights reflected from the recording medium to thereby detect an information signal and an error signal;
• and
• a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applicable for at least three lights having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums;
• wherein the optical unit further comprises a spherical aberration compensation unit for compensating for spherical aberrations occurring when using the high-density recording medium using the celadon light;
• and
• wherein the spherical aberration compensation unit comprises a zoom lens mounted to reciprocate in a direction of the optical axis of the celadon light and a driving unit for operating the zoom lens.

An optical pickup apparatus capable of compatibly employing a high-density recording medium, which uses a celadon light and is slimmer than a digital versatile disc (DVD), and at least one low-density recording medium, the optical pickup apparatus comprising:

• an optical unit for projecting a plurality of lights of different wavelengths, the lights including a celadon light, toward a recording medium and receiving the lights reflected from the recording medium to thereby detect an information signal and an error signal;
• and
• a compatible objective lens for focusing a light projected from the optical unit to thereby form an optical spot on a recording surface of the recording medium and applicable for at least three lights having different wavelength ranges to be compatibly used for both the high-density and the low-density recording mediums;
• wherein the low-density recording medium comprises the DVD and a compact disc (CD);
• and
• wherein the optical unit comprises:
• a first light source for projecting the celadon light for the high-density recording medium;
• a 2-wavelength light source module for projecting an infrared light for the CD and the red light for the DVD and receiving the lights being reflected to thereby detect a signal;
• a first light detector for receiving the light projected by the first light source and reflected from the recording medium to thereby detect a signal;
• a first optical path converter for changing a path of the light projected by the first light source;
• a second optical path converter for changing a path of the light projected by the 2-wavelength light source module;
• and
• a first monitoring light detector which receives a part of the light projected by the first light source to monitor output of the first light source;
• wherein the first monitoring light detector directs the first light source.