Abstract: An optical disk drive is disclosed including an optical system, a servo signal detector configured to obtain control information for controlling the optical system based on the output signal of a photo detector in accordance with the recording layer to be accessed, a servo controller configured to select adjustment information in accordance with the recording layer, and adjust the control information based on the selected adjustment information. When the optical disk drive accesses an optical disk having multiple recording layers, the servo signal detector can obtain the control information for controlling the optical system in accordance with the recording layer, and the servo controller can select adjustment information in accordance with the recording layer and adjust the control information based on the selected adjustment information. The above arrangements allows the optical system to be adjusted in accordance with the recording layer to be accessed.

Abstract: An information recording and reproducing system comprises a host device, and an information recording and reproducing device connected with the host device via a host interface. The host device includes a control-command issuing unit issuing a control command to the information recording and reproducing device. The control command causes a data-recording interrupting-resuming unit of the information recording and reproducing device either or not to perform the interruption and resumption of the recording. The information recording and reproducing device includes a data-recording interruption-resumption control unit controlling the data-recording interrupting-resuming unit either or not to perform the interruption and resumption of the recording, according to the control command received from the host device.

Abstract: Disclosed is an optical system for an optical disk drive for reading/writing data from/in an optical disk. The optical system includes a light source emitting a parallel laser beam, a deflector having a rotatable mirror surface. The parallel laser beam emitted by the light source is incident on the mirror surface of the deflector and is deflected towards an objective lens system which faces the optical disk. A relay lens system is provided between the deflector and the objective lens system such that the mirror surface and a front principal plane of the objective lens system have a substantially conjugate relationship.

Abstract: Disclosed is an optical data recording/reproducing device which is provided with a laser diode for emitting laser beam, an illuminating optical system including an objective lens which converges the laser beam emitted by the laser diode on an optical disc, a monitoring optical system including a light receiving element which receives a part of the laser beam emitted by the laser diode, and a driving circuit which drives the laser diode in accordance with an output signal of the light receiving element. A coupling efficiency of the illuminating optical system and a coupling efficiency of the monitoring optical system are made substantially the same.

Abstract: An information recording and reproducing system comprises a host device, and an information recording and reproducing device connected with the host device via a host interface. The host device includes a control-command issuing unit issuing a control command to the information recording and reproducing device. The control command causes a data-recording interrupting-resuming unit of the information recording and reproducing device either or not to perform the interruption and resumption of the recording. The information recording and reproducing device includes a data-recording interruption-resumption control unit controlling the data-recording interrupting-resuming unit either or not to perform the interruption and resumption of the recording, according to the control command received from the host device.

Abstract: Disclosed is an optical system for an optical disk drive for reading/writing data from/in an optical disk. The optical system includes a light source emitting a parallel laser beam, a deflector having a rotatable mirror surface. The parallel laser beam emitted by the light source is incident on the mirror surface of the deflector and is deflected towards an objective lens system which faces the optical disk. A relay lens system is provided between the deflector and the objective lens system such that the mirror surface and a front principal plane of the objective lens system have a substantially conjugate relationship.

Abstract: An lens evaluating system for evaluating a dual-focus lens is disclosed. The lens evaluating system is provided with an interferometer to form an image of interference fringes and a masking system which masks a part of the image corresponding to a noise component.

Abstract: A lens inclination adjustment system includes an interferometer unit, an inclination adjusting unit and a data processing unit. The data processing unit compares data of the interference fringes generated by the interferometer with predetermined image data to determine inclination status of the lens. Thereafter, in the adjusting unit, the current inclination status of the lens is detected. The data processing unit then calculates a target position to which the inclination status of the lens should be adjusted, and displays a position indicating the current inclination status and the target position on a screen.

Abstract: A lens adjustment system including a interferometer and an adjustment unit is used for adjusting an inclination of a lens of an optical data recording/reproducing device. The interferometer detects an inclination angle of the objective lens, then, the inclination of the lens is adjusted at the adjustment portion. There are two light sources: one is for the interferometer; and the other is for monitoring the inclination adjustment. The inclination adjustment unit has an optical element which prevents the beam projected toward the interferometer from being incident on an image receiving surface of the monitoring system, and only the beam for monitoring the inclination adjustment is observed when the inclination of the lens is being adjusted.

Abstract: An inclination status monitoring system which optically detects an inclination of a lens as it changes its inclination. A light beam having a diameter greater than the diameter of the lens to be inclined is incident on the lens. The lens has a planar reflective surface surrounding a lens portion thereof. The light beam is reflected on the reflective surface, and the reflected beam is converged by a converging lens and focused on an image receiving system, which enables a user to observe the image formed on an image receiving surface. The image of the reflected beam moves simultaneously as the lens inclination is changed.

Abstract: An inclination monitoring system for monitoring an inclination of a lens having a lens portion and a flange portion surrounding the lens portion with respect to a reference plane. The inclination monitoring system includes a light emitting system which emits a collimated light beam towards the lens. The light emitting system and the lens are arranged such that optical axes of the light emitting system and the lens form a first predetermined angle. The monitoring system is further provided with a light receiving system which receives light reflected by the lens. The light receiving system is arranged in a predetermined positional relationship with respect to the light emitting system and the lens. In particular, the collimated light beam illuminates an entire area of the flange portion.

Abstract: A collimating lens unit is provided that includes a collimating lens, a lens holder which holds the collimating lens, and an adhesive which secures the collimating lens to the lens holder. The adhesive is applied to remain outside of an effective area of the collimating lens, so that an output beam emitted from the collimating lens unit is not shaded by the adhesive. In particular, the effective area is determined based on the characteristics of an optical system which includes the collimating lens.

Abstract: A laser beam emitted from a laser diode passes through a polarizing separating plane of a first polarization beam splitter and forms a beam spot on a magneto-optic disk. The plane of polarization of the laser beam that is reflected at a magnetic film provided on the magneto-optic disk is rotated by the Kerr effect in a fixed direction depending on the direction of magnetization of the magnetic film. The reflected laser beam is made incident on the polarizing separating plane of the first polarization beam splitter. The angle of the polarizing separating plane of the first polarization beam splitter is adjusted with respect to an optic path of the laser beam so that the P polarization component of the laser beam is reflected by 20%.

Abstract: A light beam emitted from a laser diode passes through a polarization beam splitter, a movable mirror, a reference prism supported in a pair of rails, a sliding mirror and is incident on a cat's-eye optical system. The light beam reflected in the cat's-eye optical system returns to the polarization beam splitter along an optical path of the incident light beam, is separated by a polarizing separating plane and is directed to a television camera. The front surface of the reference prism is perpendicular to the rails. Thus, the light beam reflected at the front surface of the reference prism is directed to the television camera along an optical path which is inclined relative to the optical path of the incident light beam in accordance with the direction of the rails. Consequently, if the inclination of the movable mirror is adjusted such that the light spots of both of the reflected beams displayed on the monitor coincide, the optical path of the incident light beam is parallel to the rails.

Abstract: A laser beam emitted from a laser diode passes through a first polarization beam splitter to form a spot on a magnetic film of a magneto-optic disk. The plane of polarization of the laser beam reflected at the magneto-optic disk rotates, due to the Kerr effect, in a fixed direction in accordance with the direction of magnetization of the magnetic film. The laser beam then passes through a half-wave plate. The half-wave plate is attached on a base plate and tilted with respect to the optical axis of the laser beam so that its phase difference along the optical axis compensates the phase difference of the entire optic system. The laser beam passed through the half-wave plate is separated by the second beam splitter into a P polarization component and S polarization component, which are respectively detected by photodiodes.

Abstract: An optical data recording and reproducing apparatus in which a beam spot is made incident upon recording tracks of an optical recording medium, so that the beam reflected from the optical recording medium is detected to obtain a data signal and a tracking error signal. The optical recording medium is a rotatable optical disc having a signal recording surface. The recording tracks include concentrically arranged recording track sectors formed on the signal recording surface of the optical disc and preformat portions provided between the adjacent recording track sectors. A beam shape setting device is provided to shape an image of the beam spot formed on the track sectors into a non-circular shape which is elongated in the circumferential direction of the optical disc.

Abstract: A detecting apparatus which detects an inclination of an objective lens relative to a reference surface is provided. The objective lens is part of an optical data recording and reproducing apparatus in which data is optically recorded on and reproduced from a recording medium which is placed parallel to the reference surface. The apparatus includes a transparent parallel plate which is opposite the objective lens, parallel to the reference surface, and made of a material that is substantially optically equivalent to a transparent material of the recording medium. The apparatus further includes a reflecting mechanism for reflecting coherent light which has passed through the objective lens and the transparent parallel plate back towards the transparent parallel plate and the objective lens, and a beam splitting mechanism for splitting the coherent light into a first beam and a second beam.

Abstract: The optical disk apparatus of this invention is provided with a memory for memorizing a track offset signal corresponding to an angle of a galvanic mirror, or a photodetector having two pairs of photodetecting regions to detect different tracking error signals to each other, or two galvanic mirrors which are adjusted so as to prevent the track offset signal.

Abstract: A position detecting apparatus comprising a magnet secured to a movable body (lens holder) which is movable along a shaft body when the shaft body is inserted, the magnet having polarity which is alternately magnetized at a predetermined interval, and a magneto-resistance effect element which is positioned and fixed so as to be confronted to the magnet at a predetermined gap interval by an MR holder with the shaft body being used as a securing position reference, and the magneto-resistance effect element serving to obtain a position detection signal for the movable body through variation of a resistance value thereof which is caused by magnetic field of the magnet through movement of the movable body.

Abstract: A device in which an offset is added to a focusing error signal to control an objective lens and thereby reduce the generation of cross-talk when a beam spot that is converged on an optical disk crosses over a wall of a groove of a track of the disk. By adding the offset to the focusing error signal, the objective lens is moved out of focus with the disk. Thus, the shape of a beam spot formed on a photo sensor is changed from a circle to an ellipse. A condenser lens provided for forming the beam spot is moved along the optical axis thereof in such a manner that an output of a recorded signal of the disk is at a maximum value. As a result, the objective lens is brought into focus on the disk. Thereafter, the objective lens is focused on the disk in accordance with the focusing error signal to which the offset is added, while maintaining the beam spot in the shape of an ellipse.