Optical pickup apparatus having an improved holographic unit, and optical disk drive including the same

An optical pickup apparatus for accessing an optical recording medium, comprising:

• a light source unit emitting one of a plurality of laser beams having different wavelengths, the light source unit including a first laser diode emitting a laser beam having a first wavelength and a second laser diode emitting a laser beam having a second wavelength;
• an optical system focusing said one of the plurality of laser beams, emitted by the light source unit, onto a recording surface of the recording medium;
• a photodetector unit receiving reflection beams, which are reflected from the recording medium in response to said one of the plurality of laser beams focused by the optical system, to generate detection signals from the received reflection beams;
• a holographic unit having a first hologram suited to the first laser diode and a second hologram suited to the second laser diode, the first hologram provided to diffract a reflection beam of the laser beam of the first laser diode to the photodetector, the second hologram provided to diffract a reflection beam of the laser beam of the second laser diode to the photodetector, wherein the first hologram and the second hologram of the holographic unit are respectively configured into a first polarizing hologram and a second polarizing hologram;
• and
• a common quarter-wave plate provided between the holographic unit and the optical system, and the common quarter-wave plate and the holographic unit being integrally provided in a single optical module.

An optical pickup apparatus for accessing an optical recording medium, comprising:

• a light source unit emitting one of a plurality of laser beams having different wavelengths, the light source unit including a first laser diode emitting a laser beam having a first wavelength and a second laser diode emitting a laser beam having a second wavelength;
• an optical system focusing said one of the plurality of laser beams, emitted by the light source unit, onto a recording surface of the recording medium;
• a photodetector unit receiving reflection beams, which are reflected from the recording medium in response to said one of the plurality of laser beams focused by the optical system, to generate detection signals from the received reflection beams;
• a holographic unit having a first hologram suited to the first laser diode and a second hologram suited to the second laser diode, the first hologram provided to diffract a reflection beam of the laser beam of the first laser diode to the photodetector, the second hologram provided to diffract a reflection beam of the laser beam of the second laser diode to the photodetector;
• and
• a coupling mirror reflecting each of the laser beams of the first and second laser diodes to the optical system.

An optical pickup apparatus for accessing an optical recording medium, comprising:

• a light source unit emitting one of a plurality of laser beams having different wavelengths, the light source unit including a first laser diode emitting a laser beam having a first wavelength and a second laser diode emitting a laser beam having a second wavelength;
• an optical system focusing said one of the plurality of laser beams, emitted by the light source unit, onto a recording surface of the recording medium;
• a photodetector unit receiving reflection beams, which are reflected from the recording medium in response to said one of the plurality of laser beams focused by the optical system, to generate detection signals from the received beams;
• and
• a holographic unit having a first holographic pattern suited to the first laser diode and a second holographic pattern suited to the second laser diode, the first hologram provided to partially diffract a reflection beam of the laser beam of the first laser diode to the photodetector, and the first laser reflection beam partially passing through the first holographic pattern to the photodetector, the second hologram provided to partially diffract a reflection beam of the laser beam of the second laser diode to the photodetector, and the second laser reflection beam partially passing through the second holographic pattern to the photodetector.