Sony Corporation

Masaki Kagawa

Hiroshi Nakayama

Katsuhiko Ohtomo

Ayumi Konishi

Jun Nakano

Minoru Kikuchi

Hiroyuki Takemoto

Fuminori Takase

Yoshimori Yamasaki

Yoshihiro Akimoto

Nobuhiro Saito

Hiroshi Nomura

Toshio Sasaki

There are provided an inexpensive polarizing beam splitter having a polarized light beam separating function of a wide range with a simple film construction and a reduced number of laminated film layers, and a polarizer provided with the polarizing beam splitter to arrange natural light into a specific polarized state. A polarizing beam splitteris constructed including a polarized light beam separation filmin which a first polarized light beam Lof a light Lincident at a predetermined angle is transmitted and a second polarized light beam Lof the incident light Lis reflected in a direction different from the above transmitted direction, having any structure of (H2L), (H2L)H, and 2L(H2L)(where m is an integer 3 or more) , each of which is a repeated structure of a basic structure film H2L that, when &#x3bb;represents a reference wavelength of 550 nm of the incident light, is constructed of a high refractive-index layer H and low refractive-index layer L each of which has an optical film thickness approximately equal to &#x3bb;/4; and transparent substratesA,B disposed on the light-entering surfaceA side and on the light-outgoing surfaceB side of the above film, respectively. Also, a polarizer is constructed being provided with the above polarizing beam splitterand is formed by alternately laminating the polarized light beam separation film and transparent substrate to be obliquely cut out.

Polarizing beam splitter and polarizer using the same

An optical recording medium includes recording tracks located adjacently to each other and is provided on and/or from which information is recorded and/or reproduced by irradiating with a beam a predetermined track of those recording tracks. The track pitch between the adjacent recording tracks is adjusted so that the track pitch is made substantially equal to a distance between an intensity center of a beam spot on a laser beam irradiated plane of the medium and a location of an initial minimum intensity. By irradiating with a beam the predetermined track, therefore, the beam intensity is located around the center of the recording track that is adjacent to the minimum portion. This location results in reducing a crosstalk amount from the adjacent recording track to a minimum, thereby suppressing the loss of the crosstalk characteristic to a minimum. This makes it possible to enhance the recording density in the alignment direction of the recording tracks if an A/W in the optical system is 1.0 or lower, in which A denotes an effective radius of an objective lens in the alignment direction of the recording tracks and W denotes a beam spot size on the objective lens in the alignment direction of the recording tracks.

Optical recording medium

An optical recording medium includes recording tracks located adjacently to each other and is provided on and/or from which information is recorded and/or reproduced by irradiating with a beam a predetermined track of the recording tracks. The track pitch between the adjacent recording tracks is adjusted so that the track pitch is made substantially equal to a distance between an intensity center of a beam spot on a laser beam irradiated plane of the medium and a location of an initial minimum intensity. By irradiating with a beam the predetermined track, therefore, the beam intensity is located around the center of the recording track that is adjacent to the minimum portion. This location results in reducing a crosstalk amount from the adjacent recording track to a minimum, thereby suppressing the loss of the crosstalk characteristic to a minimum. This makes it possible to enhance the recording density in the alignment direction of the recording tracks if an A/W in the optical system is 1.0 or lower, in which A denotes an effective radius of an objective lens in the alignment direction of the recording tracks and W denotes a beam spot size on the objective lens in the alignment direction of the recording tracks.

Reduced crosstalk optical recording medium using an optically related track pitch

An optical disc comprising a recording layer upon which a groove and land are formed for recording a data signal upon both the groove and the land, and further wherein both of the groove and the land have substantially identical recording characteristics.

High recording density optical disc

Optical disc having specified track pitch, push-pull signal, and cross-track signal

An optical information reproducing method for demodulating the information recorded on a recording medium by a viterbi decoding method, in which data can be demodulated with high accuracy even if the recording power has undergone variations at the time of recording the information. Data recorded on the recording medium after modulation in which the minimum length between transitions is limited to not less than 2 is decoded using the viterbi decoding method. A specified signal recorded on the recording medium is used for setting the reference value used for viterbi decoding.

Optical information reproducing method and apparatus

Optical disk having pits with push-pull signal of opposite polarity to

Even if grooves are, in order to improve productivity, omitted from an optical recording medium having pits indicating information signals formed in at least a portion of recording tracks of the optical recording medium, signals having satisfactorily high levels required to perform tracking control are attempted to be obtained. The number of regions of the recording tracks in which the pits are formed is made to be larger than the number of regions in which no pit is formed. Specifically, since '0' has higher appearance probability than '1' in a case of a binary information signal consisting of '0' and '1', pits are formed at positions corresponding to '0' of the information signal.

Optical recording medium having a specified range of pit widths and pit

An optical recording medium capable of being reproduced by a conventional drive device which meets an optical disk having grooves and no groove in an area in which pits are formed. In the optical recording medium having pits 1 showing information signals in the shape of protruding and recessed parts, it is assumed that the depth t1 of the above mentioned pits t2 of the pits 1 is located within a range of 0.3 to 0.6 .mu.m. Herein, n designates the refractive index of the base of the optical recording medium and designates the wavelength of the light used for reproduction.

In an edge detection method, a tightest data portion for forming a tightest pit pattern therein is provided in an area in the front of an effective data portion where an information pit pattern is formed, and the threshold voltage is established on the basis of the tightest pit pattern formed in the tightest data portion.

Growing community of inventors

Miyagi, Japan

Masaki Kagawa