Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Mitsubishi Denki Kabushiki Kaisha

Daisuke Ogata

Hidenori Wada

Shin-ichi Kadowaki

Hiroaki Yamamoto

Seiji Nishino

Tetsuo Saimi

Yoshiaki Komma

Sadao Mizuno

Kousei Sano

Akihiro Yasuda

Katsuhiko Yasuda

Michihiro Yamagata

Yasuhiro Tanaka

Yuuichi Kuze

Tomohiko Sasano

Naoya Hotta

Kanji Wakabayashi

Hideki Hayashi

Kazuhiro Hayashi

Shigeru Furumiya

Katsuya Watanabe

Kenji Koishi

Ken'ichi Kasazumi

Takashi Yumura

Takaharu Ueda

Masahiro Inata

Yoshihiro Kanda

Tetsu Yamamoto

Yoshihiro Ikawa

Yuichi Kamioka

Jouji Anzai

Shigeki Mizuno

Kiyoshi Funai

Shunji Oohara

An optical pickup head is provided with a light source, a diffracting means for creating a plurality of diffracted beams, a converging means for focusing the diffracted beams onto an optical storage medium, a beam branching means for branching the plurality of beams reflected by the optical storage medium, and an optical detecting means for outputting a signal corresponding to the amount of light of the received beams. The optical detecting means has main beam light receiving portions and sub-beam light receiving portions. The amount of light of the first or higher order diffracted beams when they are substantially focused on and reflected by a focus plane of the plurality of information recording planes is equal to or greater than the amount of light of the zero order diffracted beam when it is reflected without focusing by a non-focus plane other then the focus plane of the plurality of information recording planes. The invention provides an optical pickup head where offset is not generated in the TE signals even during tracking with the objective lens when a two-layered disk is used.

Optical pickup head and information recording/reproducing device

Disclosed is an optical head apparatus comprising: a light source; a collimating means of converting a beam of light emitted from the light source into a substantially parallel beam of light; a focusing means of focusing the light onto an information medium surface; a beam splitting means of splitting the beam of light modulated by the information medium; and a light receiving means of receiving the light modulated by the information medium, wherein a lens having a negative power and a lens having a positive power are arranged in this order as viewed from the collimating means side between the collimating means and the focusing means, and at least either one of the lenses is moved along an optical axis to correct spherical aberration occurring on the information medium surface, and wherein the distance from the lens having the positive power to the focusing means is set substantially equal to the focal length of the lens having the positive power.

Optical head apparatus and optical information recording and reproduction apparatus

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, a first opposing electrodearranged in opposition to the first voltage application electrode, and a first phase changing layerarranged between the first voltage application electrodeand the first opposing electrode. By changing a voltage between the first voltage application electrodeand the first opposing electrode, a phase that converts plane waves into spherical waves is imparted on light that is incident on the first phase changing layer

Optical element, optical head, optical recording reproducing apparatus and optical recording/reproducing method

An optical head includes a laser source () irradiating the laser beam having a wavelength not longer than 500 nm, a collimator lens () for collimating the laser beam to the parallel rays, an optical beam shaping system () that adjusts the cross sectional shape of the beam from the collimator lens, and an objective lens () that converges the beam on an optical information medium. The optical head has a relationship between a focal length fof the collimator lens and a magnification M of beam shaping satisfies the following equation: in which C is a constant in (&#x3bb;&#xb7;mm), Ais a maximum astigmatism per displacement of the collimator lens from the focal position, and n is a refractive index of a member of optical beam shaping system.

Optical head and optical disc apparatus for focusing a collimated laser beam

An optical head for recording or reproducing a signal with respect to an optical recording medium, which includes an optical element disposed between a light source and an optical recording medium. The optical element has an optically active polymer film in which an optical rotation property changes with respect to an applied voltage, a pair of conductive transparent thin films for applying a voltage to the optically active polymer film, and a transmittance polarization anisotropic part having a different transmittance with respect to a polarization direction, which is disposed on one of the conductive transparent thin films. By changing the applied voltage to the optically active polymer film, a light quantity of a linearly polarized light transmitted through the optical element can be changed substantially instantaneously. Therefore, the power of light reaching the optical recording medium can be switched substantially instantaneously at the time when switched between recording and reproduction.

Optical head including an active polymer film for switching voltage during recording and reproducing processes

The quantity of spherical aberration correction is predetermined for each recording plane of an optical disk on which focusing control is performed. Before operating the focusing control, the quantity of spherical aberration to be corrected by an aberration correcting system is set based on an output signal from an aberration correction quantity switching device that corresponds to the type of the optical disk and the recording plane to be subjected to the focusing control. This makes it possible to perform stable focusing control on each recording plane of a multi-layer optical disk with high density by using an objecting lens having a large NA after spherical aberration has been corrected properly.

Optical disk apparatus

Optical element, optical head, optical recording reproducing apparatus and optical recording/ reproducing method

Tilt which is inclination of a normal of optical disk relative to optical axis of optical head is corrected with a liquid crystal element. In a driver for the liquid crystal element, a periodic waveform generator generates periodic waveform and an inverting element inverts the periodic waveform. The periodic waveform and the inverted waveform are connected to two ends of a potential divider which provides partial voltages. The periodic waveform is connected to a common electrode of the liquid crystal element, and the partial voltages of the potential divider are connected to electrodes opposing the common electrode. A structure of a driver circuit for each direction is simple. Tilt in a plurality of directions can be performed independently of each other. Spherical aberration is also corrected. When the liquid crystal element is mounted to a fixed component, deterioration due to jitters is reduced.

Liquid crystal driver and optical head for tilt correction

An optical information recording medium in which the ranges of the refractive index and thickness of a protective layer in a case where the protective layer is constituted by a plurality of layers are newly specified and the refractive index and thickness of the protective layer are determine in these ranges, thereby ensuring that even if variation in thickness of the protective layer to &#xb1;3 &#x3bc;m is tolerated, spherical aberration in the optical information recording medium is substantially to within 30 m&#x3bb;rms.

Optical information recording medium, optical information recording/reproduction method, and optical information recording/reproduction apparatus

Growing community of inventors

Amagasaki, Japan

Daisuke Ogata