Hitachi Maxell, Limited

Toyoyuki Nunomura

Toshiaki Taii

Hiroshi Nagate

Masashi Suenaga

Tamotsu Iida

Yusuke Takahashi

Atsuki Hirose

Katsunori Miyata

An optical information-recording medium has a plurality of lands and grooves formed on a substrate. In-groove pits are formed at the bottom of a part of the grooves. The widths of the in-groove pits in the radial direction of the substrate are suppressed from being widened irrelevant to the lengths in the groove direction. Predetermined shapes of the land and the groove are maintained for the shape of the land disposed adjacently to the in-groove pit without greatly eroding or scraping the side wall. A recording signal obtained from land prepits can be reliably detected on the optical information-recording medium manufactured by using the substrate formed with the land prepits disposed adjacently to the in-groove pits.

Optical information-recording medium and method for producing the same

An optical apparatus for an optical information recording medium including a light source, two acoustooptical elements for modulating the light beam emitted from the light source and an objective lens for focusing the light beam emitted from the acoustooptical elements to the optical information recording medium, the acoustooptical elements being provided in an optical path extending from the light source to the objective lens arranged such that directions of travel of supersonic waves generated in the respective acoustooptical elements are crossed to each other.

Optical apparatus for optical information recording medium

An optical information recording medium in which pre-pits longer than the diameter of a reproducing radiation spot and pre-pits shorter than the diameter of the reproducing radiation spot coexist, the width W of the pre-pit longer than the diameter of the reproducing radiation spot being formed with a value satisfying a relation of .PHI./4&lt;W&lt;.PHI./3, wherein .PHI. is the diameter of the reproducing radiation spot and a method of fabricating the optical information recording medium comprising setting a power of a radiation beam when a pre-pit shorter than the diameter of the reproducing radiation spot among a plurality of pre-pits to be formed for each sector is cut to a predetermined optimum value, setting a power of the radiation beam when the pre-pit longer than the diameter of the reproducing radiation spot is cut to a predetermined value smaller than the predetermined optimum value of the radiation beam power when the pre-pit shorter than the diameter of the reproducing radiation spot is cut, and performing the cutting of pre-pits while combining the radiation beam power at the predetermined optimum value when the pre-pit shorter than the diameter of the reproducing radiation spot is cut with the radiation beam power at the predetermined smaller value when the pre-pit longer than the diameter of the reproducing radiation spot is cut.

Optical information recording medium and method of fabricating the same

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Ibaraki, Japan

Toyoyuki Nunomura