摘要:
An optical disk device is provided with an optical pickup that includes a convergent optical system having an objective lens for converging a light beam emitted from the laser light source to form a microspot on an optical disk and an aberration correcting optical system for controlling a spherical aberration of the convergent optical system, and performs information recording or reproduction with respect to a multi-layer optical disk having at least a first recording layer and a second recording layer. In the optical disk device, an operation of changing a correction quantity of the spherical aberration from a value adequate for the first recording layer to a predetermined value is started before an operation of moving a focus position of the microspot from the first layer to the second layer is completed. This allows a focus control to be performed stably with respect to the second recording layer in a state in which the spherical aberration correction already has been carried out, thereby preventing the focus control from failing due to an unsuccessful interlayer jump.
摘要:
An optical head device includes a focusing optical system for focusing a laser beam emitted from a semiconductor laser light source on an optical information medium with an objective lens. A chromatic aberration correction element for correcting chromatic aberration occurring in the objective lens is provided between the semiconductor laser light source and the optical information medium. A light distribution correction element in which the transmittance increases with the distance from the center of the aperture surface of the objective lens is provided so as to correct a reduction of the intensity of the light incident on the aperture surface of the objective lens with the distance from the center of the aperture surface.
摘要:
An optical disk device is provided with an optical pickup that includes a convergent optical system having an objective lens for converging a light beam emitted from the laser light source to form a microspot on an optical disk and an aberration correcting optical system for controlling a spherical aberration of the convergent optical system, and performs information recording or reproduction with respect to a multi-layer optical disk having at least a first recording layer and a second recording layer. In the optical disk device, an operation of changing a correction quantity of the spherical aberration from a value adequate for the first recording layer to a predetermined value is started before an operation of moving a focus position of the microspot from the first layer to the second layer is completed. This allows a focus control to be performed stably with respect to the second recording layer in a state in which the spherical aberration correction already has been carried out, thereby preventing the focus control from failing due to an unsuccessful interlayer jump.
摘要:
The invention presents an optical element with which an optical head can be configured, in which there is little deterioration of the correctional effect when the objective lens shifts, as well as an optical head and an optical recording/reproducing apparatus using such an optical element. The invention also presents a novel optical recording/reproducing apparatus and optical recording/reproducing method. The optical element, includes a first voltage application electrode 13, a first opposing electrode 17 arranged in opposition to the first voltage application electrode 13, and a first phase changing layer 15 arranged between the first voltage application electrode 13 and the first opposing electrode 17. By changing a voltage between the first voltage application electrode 13 and the first opposing electrode 17, a phase that converts plane waves into spherical waves is imparted on light that is incident on the first phase changing layer 15.
摘要:
The invention presents an optical element with which an optical head can be configured, in which there is little deterioration of the correctional effect when the objective lens shifts, as well as an optical head and an optical recording/reproducing apparatus using such an optical element. The invention also presents a novel optical recording/reproducing apparatus and optical recording/reproducing method. The optical element, includes a first voltage application electrode 13, a first opposing electrode 17 arranged in opposition to the first voltage application electrode 13, and a first phase changing layer 15 arranged between the first voltage application electrode 13 and the first opposing electrode 17. By changing a voltage between the first voltage application electrode 13 and the first opposing electrode 17, a phase that converts plane waves into spherical waves is imparted on light that is incident on the first phase changing layer 15.
摘要:
An optical head device includes a light source for emitting light; an optical system for focusing the light emitted by the light source onto an information medium to form a light spot; a photodetector including a plurality of light detection areas for receiving the light reflected by the information medium and for outputting photocurrents in accordance with the respective amount of the light received; a holographic optical element for diffracting the light reflected by the information medium and for directing the light to the photodetector; and a signal processing circuit section for obtaining a focusing error signal and a tracking error signal for controlling the light spot using the photocurrents. The signal processing circuit section obtains the focusing error signal from the photocurrents which are obtained in accordance with the amount of light of one of .+-.Nth-order diffracted beams, and obtains the tracking error signal from the photocurrents which are obtained in accordance with the amount of light of the other of the .+-.Nth-order diffracted beams.
摘要:
An optical head apparatus consists of a light beam source, a blazed hologram partitioned into diffraction regions for mainly changing the light beam radiated from the light beam source to zero-order diffraction light and secondarily diffracting the light beam to produce beams of unnecessary light such as N-order diffraction light (N.noteq.0), an information medium for storing information, an objective lens for converging the zero-order diffraction light and the unnecessary light at the information medium, and a six-division photo detector having six detecting sections for detecting intensity of first-order diffraction light produced by diffracting the zero-order diffraction light in the blazed hologram. A hologram pattern of the blazed hologram is formed to function as a lens for the unnecessary light. A focus servo signal is produced according to mutual relation among intensities of the first-order diffraction light detected in the six detecting sections to focus the objective lens on the information medium For the zero-order diffraction light. Therefore, the objective lens is not focused on the information medium for the unnecessary light. Also, the beams of the unnecessary light diffracted in each of the diffraction regions of the blazed hologram are greatly widened because numerical apertures of the diffraction regions are small.
摘要:
An optical pickup apparatus in which light from a light source is led to an information medium and reflected light from the information medium is led to a hologram to be incident as a +1st order diffraction beam on a photodetector to obtain information signals. The hologram has a stair-like cross-sectional configuration, and a ratio of the width of a step of the stair-like cross-sectional configuration relative to a grating pitch of the hologram is arranged to vary in accordance with a position within a surface of the hologram.
摘要:
A compound objective lens is composed of a hologram lens or transmitting a part of incident light without any diffraction to form a beam of transmitted light and diffracting a remaining part of the incident light to form a beam of first-order diffracted light, and an objective lens for converging the transmitted light to form a first converging spot on a front surface of a thin type of first information medium and converging the diffracted light to form a second converging spot on a front surface of a thick type of second information medium. Because the hologram selectively functions as a concave lens for the diffracted light, a curvature of the transmitted light differs from that of the diffracted light. Therefore, even though the first and second information mediums have different thicknesses, the transmitted light incident on rear surface of the first information medium is converged on the its front surface, and the diffracted light incident on a rear surface of the second information medium is converged on the its front surface. That is, the compound objective lens has two focal points.
摘要:
An optical disk device is provided with an optical pickup that includes a convergent optical system having an objective lens for converging a light beam emitted from the laser light source to form a microspot on an optical disk and an aberration correcting optical system for controlling a spherical aberration of the convergent optical system, and performs information recording or reproduction with respect to a multi-layer optical disk having at least a first recording layer and a second recording layer. In the optical disk device, an operation of changing a correction quantity of the spherical aberration from a value adequate for the first recording layer to a predetermined value is started before an operation of moving a focus position of the microspot from the first layer to the second layer is completed. This allows a focus control to be performed stably with respect to the second recording layer in a state in which the spherical aberration correction already has been carried out, thereby preventing the focus control from failing due to an unsuccessful interlayer jump.