Sony Corporation

Nec Corporation

Sony Corportion

Ariyoshi Nakaoki

Katsuhisa Aratani

Masahiko Kaneko

Nobuhiko Umezu

Kimihiro Saito

Akira Kouchiyama

Osamu Kawakubo

Akira Suzuki

Kenji Yamamoto

Takeshi Yamasaki

Toshiyuki Kashiwagi

Kazuhiko Fujiie

Tsutomu Ishimoto

Tetsuhiro Sakamoto

Takao Kondo

Tomiji Tanaka

Shintaro Tanaka

Naoto Kojima

Koji Sekiguchi

Yoshihiro Muto

Takashi Shimouma

Sunmin Kim

Kayoko Suzuki

An optical pickup device has a near-field optical system having a numerical aperture of NA&#x3e;1; a first light source emitting a first light having a first wavelength; a second light source emitting a second light having a second wavelength; an optical system multiplexing the first light and second light and irradiating the multiplexed light onto an optical recording medium having at least two recording layers; a first photodetector detecting the first light returned from the recording medium a second photodetector detecting the second light returned from the recording medium; a controller obtaining a signal corresponding to distance between the near-field optical system and the recording medium based on the returned second light, and obtaining a reproducing signal and a tracking signal of the recording medium and a focus signal corresponding to the recording layer based on the returned first light; and a focus position adjustment mechanism moving a focus position of the first light under control of the focus signal.

Optical pickup device and recording/reproducing device

A solid immersion lens (SIL) is provided. The SIL includes a spherical part, a cone-shaped part, a tip part, and an edge part between the cone-shaped part and the tip part. The edge part includes a curved surface.

Solid immersion lens and focusing lens, optical pickup device, and data recording/reproducing apparatus using the same

A signal detecting device includes: a semiconductor substrate; a near-field light generating section that is provided on the semiconductor substrate and generates near-field light near an interface with the semiconductor substrate; a light source that outputs light having wavelength corresponding to photon energy about a half as large as band-gap energy of a material of the semiconductor substrate; and a current detecting unit that detects a photocurrent generated in the semiconductor substrate when the near-field light is generated.

Signal detecting device and signal detecting method

An optical recording medium illuminated by light from a light source as near-field light using a focusing lens whose numerical aperture exceeds 1 to perform recording and/or reproduction is provided, wherein a composite layer in which a high refractive index material portion having a refractive index higher than that of a light-transmissible material portion is mixed in the light-transmissible material portion is provided on the surface of a light incident side of the optical recording medium. With an average refractive index of the composite layer being high, a numerical aperture controlled by a refractive index of a surface layer can be made large to obtain higher resolution and higher durability against contact with a lens or the like.

Optical recording medium as well as optical recording and reproduction method

A multilayer optical disk having an information storage layer which can as well as be reproduced by a general purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The method of manufacturing a multilayer disk comprises the steps of forming a first substrate having a first information storage area enabling reproduction of information therein with a first light beam having a wavelength of 770 nm to 830 nm; forming a second substrate having a second information storage area enabling reproduction of information therein with a second light beam having a wavelength of 615-655 nm but which is relatively transparent with respect to said first light beam; and bonding said first substrate to said second substrate together without said first and second said information areas facing each other.

Multilayer optical disk

An optical device is provided which has a light converging unit for converging the light illuminated on a magneto-optical recording layer of an optical recording medium and a magnetic field generating unit provided on the light converging unit towards the optical recording medium. The diameter of the light beam radiated on the magneto-optical recording layer of the optical recording medium is controlled by a light transmitting hole of the magnetic field generating unit. The light beam illuminated on the magneto-optical recording layer of the optical recording medium is not fluctuated in diameter so that it is possible to produce a magnetic field at a low power consumption. In addition, the magnetic field generating unit is not liable to be ruptured. There is also provided a recording and/or reproducing apparatus employing this optical device.

Sil magneto-optic transducer having thin film magnetic coil and holded magnetic core

An optical disk includes at least two information recording layers on one side of the disk and at least the first information recording layer from the light incident side is of an erasable type formed with a material such as bismuth-substituted magnetic garnet or cobalt ferrite which has an extinction coefficient, a coefficient of an imaginary part of a complex index of refraction, being not more than 1.0, but not less than 0.5, and gives a large magneto-optic effect and a small light absorptivity.

Optical disk and optical information recording/reproducing apparatus

The object of the present invention is to improve the accuracy of a recording signal and a reproduction signal of a magneto-optical recording medium. In a magneto-optical recording medium (,) having at least a metallic reflection layer (,), a back dielectric layer (,), a magneto-optical recording layer (,) and a light transmitting dielectric layer (,) sequentially provided on a substrate (,), the thickness of the light transmitting dielectric layer (,) closer to a convergent lens (,) is set at 50 to 80 nm. Alternatively, the refraction index n of the light transmitting dielectric layer (,) is selected to satisfy the relationship of n,&times;0.8&lE;n with the refraction index n,of the convergent lens (,).

Magneto-optical disk system having a relation between a numerical aperture of an objective lens and the thickness of a cover layer

A magneto-optical recording medium comprising a light-transmitting substrate 1 on which a dielectric layer 2, a memory layer 3 having perpendicular magnetic anisotropy, an intermediate layer 4 having in-plane magnetic anisotropy or slight perpendicular magnetic anisotropy, a recording layer 5 having perpendicular magnetic anisotropy, a dielectric layer 6, a metal layer 7, and a protective layer 8 are formed in a stacked form, the recording medium adapted to be magnetized for recording by a process comprising the step of modulating a first thermal condition and a second thermal condition according to a recording signal, wherein a stacked film 9 composed of the memory layer 3, the intermediate layer 4 and the recording layer 5 has a total thickness of from 1000 to 1500 .ANG., the dielectric layer 6 has a thickness of from 500 to 1500 .ANG., and the metal layer 7 has a thickness of from 250 to 1500 k. The magneto-optical recording medium permits a recording laser light to be used with an increased power margin, without causing any increase in the laser power level. Where the thickness of the memory layer is set in the range from 20 to 70 nm, an enhanced reproduction signal output is obtained.

Magneto-optical recording medium

A recording/reproducing apparatus for use with a photomagnetic recording medium. The apparatus comprises a magnetic coil and an optical system having a numerical aperture (NA) greater than 0.8 and arranged such that an optical axis thereof traverses the center of the magnetic coil. The photomagnetic recording medium has a magneto-optic recording film and a transparent protective layer having a thickness HCO formed sequentially on a substrate. The magnetic coil and the optical system are arranged on the transparent protective layer side of the photomagnetic recording medium when the photomagnetic recording medium is used with the apparatus and such that a combined distance equal to the thickness HCO and a distance d between a surface of the magnetic coil and an adjacent surface of the photomagnetic recording medium has a value of 0 .mu.m.ltoreq.d.ltoreq.145 .mu.m. The thickness HCO of the transparent protective layer may have a value of 0 .mu.m.ltoreq.HCO.ltoreq.100 .mu.m, and the distance d may have a value not larger than 45 .mu.m. Additionally, an innermost radius Ri of the magnetic coil may have a value of 290 .mu.m or less.

Recording/reproducing apparatus and a magneto-optical recording medium

An optical recording medium according to the present invention includes a base layer having an information signal portion formed on a surface on the side on which laser light is incident, and a light transmissive layer formed on the base layer. A thickness t of the light transmissive layer is within the range of t=3 to 177 .mu.m at least in an area of the information signal portion. If unevenness of the light transmissive layer is .DELTA.t, N.A. of an optical system for reproduction or recording and reproduction and a wavelength .lambda. satisfies .DELTA.t.ltoreq..+-.5.26 (.lambda./N.A..sup.4) (.mu.m). A track pitch is P and a skew is .THETA., then P.ltoreq.0.64 .mu.m and .THETA..ltoreq..+-.84.115.degree. (.lambda./N.A..sup.3 /t) are satisfied. The optical recording medium is recorded or reproduced by a recording and reproducing system satisfying .lambda..ltoreq.0.68 .mu.m and N.A./.lambda..gtoreq.1.20. The optical recording medium permits a recording capacity of 8 GB.

Optical recording medium and optical disk apparatus

A multilayer optical disk having an information storage layer which can as well as be reproduced by a general purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The multilayer disk has a first substrate on which is formed a first information storage layer which is relatively highly reflective with respect to a light beam having a wavelength of 770-830 nm; and a second substrate on which is formed a second information layer which is relatively transparent with respect to a light beam having a first substrate on which is formed a wavelength of 770 mn to 830 nm but which is sufficiently reflective with respect to a light beam having a wavelength of 615-655 nm.

A recording/reproducing apparatus for use with a photomagnetic recording medium. The apparatus comprises a magnetic coil and an optical system having a numerical aperture (NA) greater than 0.8 and arranged such that an optical axis thereof traverses the center of the magnetic coil. The photomagnetic recording medium has a magneto-optic recording film and a transparent protective layer having a thickness HCO formed sequentially on a substrate. The magnetic coil and the optical system are arranged on the transparent protective layer side of the photomagnetic recording medium when the photomagnetic recording medium is used with the apparatus and such that a combined distance equal to the thickness HCO and a distance d between a surface of the magnetic coil and an adjacent surface of the photomagnetic recording medium has a value of 0 .mu.m.ltoreq.d.ltoreq.145 .mu.m. The thickness HCO of the transparent protective layer may have a values of 0 .mu.m.ltoreq.HCO.ltoreq.100 .mu.m, and the distance d may have a value not larger than 45 .mu.m. Additionally, an innermost radius Ri of the magnetic coil may have a value of 290 .mu.m or less.

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Tokyo, Japan

Ariyoshi Nakaoki