Asahi Kogaku Kogyo Kabushiki Kaisha

Other

Toshiyuki Kase

Hiroshi Nishikawa

Isao Okuda

Masahiro Oono

Tsuyoshi Itoh

Koichi Maruyama

Makoto Iki

Suguru Takishima

Katsuki Hayashi

Hiroshi Yamamoto

Ryota Ogawa

Masahiko Sasaki

Hisashi Konno

Masato Noguchi

Isao Takahashi

Takashi Morita

Amit Jain

Wataru Kubo

Ryoichi Nakanishi

Ryoto Ogawa

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.

Optical system for optical disk drive

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.

Optical data recording/reproducing device

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.

Evaluating system for a dual focus lens

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.

Lens inclination adjustment system using an interferometer

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.

Lens Inclination Adjustment System

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.

Inclination monitoring system

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.

Inclination monitoring system including reflection of collimated light

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.

Collimating lens unit

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%.

Information reproducing device

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.

Method of adjusting beam axis of optical pick-up

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.

Phase compensation of optical elements by tilting a half wave plate in a

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.

Optical data recording and reproducing apparatus including non-circular

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. The apparatus further includes a wavefront rotating mechanism for rotating the first beam and the second beam about an optical axis in a manner such that the first beam and the second beam are rotated through 180 degrees with respect to one another, and a mechanism for superposing the first beam and the second beam to produce an optical interference.

Inclination of an objective lens in an optical information system

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.

Optical disk apparatus

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.

Growing community of inventors

Tokyo, Japan

Toshiyuki Kase