Abstract: A near-field optical disk apparatus, which can perform stable focus pull-in even when overshoot occurs, and a focus pull-in method, of which the method includes: raising an actuator, and monitoring and determining whether light focused on a disk is near-field light; holding or storing a driving voltage of the actuator if the light focused on the disk is the near-field light; raising the actuator, and determining a maximum driving voltage of the actuator; and performing focus pull-in while lowering the actuator in an interval where a driving voltage of the actuator is between the maximum driving voltage and the held or stored driving voltage.

Abstract: A compatible optical pickup includes an optical disc, an objective lens, a diffractive device, and a divergent lens. The optical unit emits a short wavelength light beam corresponding to a high density optical disc and a long wavelength light beam corresponding to a low density optical disc. The objective lens forms a light spot on the high density optical disc and the low density optical disc and the diffractive device diffracts the short wavelength light beam to correct chromatism according to a change in a wavelength of the short wavelength light beam. The divergent lens refracts the long wavelength light beam toward the objective lens to increase a working distance with respect to the low density optical disc.

Abstract: An optical disc apparatus and a wobble signal detection method in which a light beam projected onto an optical disc and reflected by the optical disc is divided into at least four light regions in the direction corresponding to the radial direction of the optical disc to detect the light regions, and a wobble signal is detected by performing a subtraction on first and second difference signals, the first difference signal obtained by performing a subtraction on detection signals for the inner light regions of the divided and/or detected light beam and the second difference signal obtained by performing a subtraction on detection signals for the outer light regions of the divided and/or detected light beam.

Abstract: A compatible optical pickup for recording and/or reproducing information on/from multiple kinds of optical discs having different thicknesses by selectively using source lights of respective different wavelengths corresponding to a kind of disc and using a common objective lens. At least one phase compensator, which compensates a phase of a light having a particular wavelength to correct for spherical aberration due to a thickness difference between the kinds of optical discs and/or chromatic aberration due to a wavelength difference between the required source lights, is positioned between the source lights and an entrance pupil of the objective lens. Each phase compensator compensates light of at least one wavelength and passes light of at least one other wavelength without significant relative phase alteration. By using two phase compensators, the optical pickup may be made compatible with at least three kinds of optical discs.

Abstract: A hybrid disk useable with a recording and or reproducible apparatus having an optical pickup. The hybrid disk includes a first recording layer having a first format on which data is recordable or readable by a first format beam and a second recording layer having a second format on which the data is recordable or readable by a second format beam. The transmivities and reflectivities of the first and second recording layers are interrelated to control relative intensities of the first and second format beams incident on the optical pickup.

Abstract: A data reproducing method reproducing data recorded in a super resolution information storage medium in a form of marks having magnitudes less than a resolving power of an incident light beam, and an apparatus thereof. The data reproducing method includes irradiating a first beam having a resolving power causing a super resolution phenomenon and a second beam having a resolving power not causing a super resolution phenomenon into different places on the information storage medium, detecting a first reproduction signal based on the first beam and a second reproduction signal based on the second beam, and compensating for and calculating a temporal delay between the first reproduction signal and the second reproduction signal. Therefore, a signal reflected from a peripheral area of a reproduction beam spot other than a super resolution area can be excluded, thereby improving reproduction signal characteristics.

Abstract: An optical head includes a substrate, a laser diode, a photodetector, an objective lens, a prism, and an optical element. The laser diode is installed on the substrate and emits light. The photodetector is installed on the substrate and receives the light. The objective lens is installed on a first side of the substrate and focuses the light emitted from the laser diode onto a recording surface of a disc. The prism is installed on a second side of the substrate, transmits the light emitted from the laser diode toward the objective lens, and transmits the light reflected from the recording surface toward the photodetector. The optical element adjusts an optical path formed between the substrate and the prism.

Abstract: An optical recording medium having groove tracks and land tracks, first wobbles formed along both sidewalls of each of the groove tracks, second wobbles formed along both sidewalls of each of the land tracks and which are independent of the formation of the first wobble. A middle portion is formed at a predetermined position on each of the sidewalls between adjacent pairs of the land and groove tracks. This optical recording medium can significantly reduce the non-recordable area as compared to conventional optical recording media, resulting in a great improvement in recording density.

Abstract: An optical head includes a substrate, a laser diode, a photodetector, an objective lens, a prism, and an optical element. The laser diode is installed on the substrate and emits light. The photodetector is installed on the substrate and receives the light. The objective lens is installed on a first side of the substrate and focuses the light emitted from the laser diode onto a recording surface of a disc. The prism is installed on a second side of the substrate, transmits the light emitted from the laser diode toward the objective lens, and transmits the light reflected from the recording surface toward the photodetector. The optical element adjusts an optical path formed between the substrate and the prism.

Abstract: A compatible optical pickup includes an optical disc, an objective lens, a diffractive device, and a divergent lens. The optical unit emits a short wavelength light beam corresponding to a high density optical disc and a long wavelength light beam corresponding to a low density optical disc. The objective lens forms a light spot on the high density optical disc and the low density optical disc and the diffractive device diffracts the short wavelength light beam to correct chromatism according to a change in a wavelength of the short wavelength light beam. The divergent lens refracts the long wavelength light beam toward the objective lens to increase a working distance with respect to the low density optical disc.

Abstract: A compatible optical pickup for recording and/or reproducing information on/from multiple kinds of optical discs having different thicknesses by selectively using source lights of respective different wavelengths corresponding to a kind of disc and using a common objective lens. At least one phase compensator, which compensates a phase of a light having a particular wavelength to correct for spherical aberration due to a thickness difference between the kinds of optical discs and/or chromatic aberration due to a wavelength difference between the required source lights, is positioned between the source lights and an entrance pupil of the objective lens. Each phase compensator compensates light of at least one wavelength and passes light of at least one other wavelength without significant relative phase alteration. By using two phase compensators, the optical pickup may be made compatible with at least three kinds of optical discs.

Abstract: An optical disc apparatus and a wobble signal detection method in which a light beam projected onto an optical disc and reflected by the optical disc is divided into at least four light regions in the direction corresponding to the radial direction of the optical disc to detect the light regions, and a wobble signal is detected by performing a subtraction on first and second difference signals, the first difference signal obtained by performing a subtraction on detection signals for the inner light regions of the divided and/or detected light beam and the second difference signal obtained by performing a subtraction on detection signals for the outer light regions of the divided and/or detected light beam.

Abstract: An optical recording medium having groove tracks and land tracks, first wobbles formed along both sidewalls of each of the groove tracks, second wobbles formed along both sidewalls of each of the land tracks and which are independent of the formation of the first wobble. A middle portion is formed at a predetermined position on each of the sidewalls between adjacent pairs of the land and groove tracks. This optical recording medium can significantly reduce the non-recordable area as compared to conventional optical recording media, resulting in a great improvement in recording density.