Optical pickup and disk drive apparatus

An optical pickup that is configured to record or reproduce an information signal for a plurality of different types of disk-like recording media using different wavelengths, the optical pickup being configured to irradiate a laser beam that includes a wavelength that corresponds to one of the plurality of different types of disk-like recording media and that is emitted from a photoemission element onto a disk-like recording medium through an objective lens, the optical pickup comprising:

• a diffraction element configured to split the laser beam that includes the wavelength that corresponds to one of the plurality of different types of disk-like recording media into a main beam, a pair of first sub-beams, and a pair of second sub-beams, the diffraction element including a first region configured to split a portion of the laser beam that is incident on the first region into the main beam and the pair of first sub-beams, the diffraction element including a second region configured to split a portion of the laser beam that is incident on the second region into the main beam and the pair of second sub-beams, the diffraction element being arranged in the optical pickup such that the pair of first sub-beams form a pair of first sub-beam spots on a recording surface of the disk-like recording medium and the pair of second sub-beams form a pair of second sub-beam spots on the recording surface of the disk-like recording medium such that:
• D=(2n−1)×P/2
• wherein D is a distance between a spot center of one of the pair of first sub-beam spots and a spot center of one of the pair of second sub-beam spots, the one of the pair of first sub-beam spots and the one of the pair of second sub-beam spots being spaced in a substantially radial direction of the disk-like recording medium, n is a natural number, and P is a track pitch of the disk-like recording medium.

A disk drive apparatus comprising:

• a disk table configured to receive and rotate a disk-like recording medium;
• and
• an optical pickup that includes an objective lens driving unit that is supported on a moving base that is configured to move in a radial direction of the disk-like recording medium, the optical pickup being configured to irradiate a laser beam on the disk-like recording medium through an objective lens;
• the optical pickup including
• a diffraction element configured to split the laser beam emitted from the photoemission element into a main beam, a pair of first sub-beams, and a pair of second sub-beams, the diffraction element including a first region configured to split a portion of the laser beam emitted from the photoemission element that is incident on the first region into the main beam and the pair of first sub-beams, the diffraction element including a second region configured to split a portion of the laser beam that is incident on the second region into the main beam and the pair of second sub-beams, the diffraction element being arranged in the optical pickup such that the pair of first sub-beams form a pair of first sub-beam spots on a recording surface of the disk-like recording medium and the pair of second sub-beams form a pair of second sub-beam spots on the recording surface of the disk-like recording medium such that:
• D=(2n−1)×P/2
• wherein D is a distance between a spot center of one of the pair of first sub-beam spots and a spot center of one of the pair of second sub-beam spots, the one of the pair of first sub-beam spots and the one of the pair of second sub-beam spots being spaced in a substantially radial direction of the disk-like recording medium, n is a natural number, and P is a track pitch of the disk-like recording medium.

A disk drive apparatus configured to record or reproduce an information signal for a plurality of different types of disk-like recording media using different wavelengths, the disk drive apparatus comprising:

• a disk table configured to receive and rotate a disk-like recording medium;
• and
• an optical pickup that includes an objective lens driving unit that is supported on a moving base that is configured to move in a radial direction of the disk-like recording medium, the optical pickup being configured to irradiate a laser beam on the disk-like recording medium through an objective lens, the laser beam including a wavelength that corresponds to the type of the mounted disk-like recording medium, the optical pickup including
• a diffraction element configured to split the laser beam that includes the wavelength that corresponds to one of the plurality of different types of disk-like recording media into a main beam, a pair of first sub-beams, and a pair of second sub-beams, the diffraction element including a first region configured to split a portion of the laser beam that is incident on the first region into the main beam and the pair of first sub-beams, the diffraction element including a second region configured to split a portion of the laser beam that is incident on the second region into the main beam and the pair of second sub-beams, the diffraction element being arranged in the optical pickup such that the pair of first sub-beams form a pair of first sub-beam spots on a recording surface of the disk-like recording medium and the pair of second sub-beams form a pair of second sub-beam spots on the recording surface of the disk-like recording medium such that:
• D=(2n−1)×P/2
• wherein D is a distance between a spot center of one of the pair of first sub-beam spots and a spot center of one of the pair of second sub-beam spots, the one of the pair of first sub-beam spots and the one of the pair of second sub-beam spots being spaced in a substantially radial direction of the disk-like recording medium, n is a natural number, and P is a track pitch of the disk-like recording medium.