Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Makoto Aihara

Osamu Ishizaki

Tsuyoshi Maro

Hideo Daimon

Hiroyuki Hirata

Tatsuo Araki

Yasuhiko Kokufuda

Masashi Yoshimura

Susumu Shibasaki

Hideki Komiya

Shuji Seki

A method of producing an optical element, in which a first and a second die are cooperated with each other so as to press-mold a material in order to produce an optical element including a lens portion, the first die has a circular cross-sectional shape, and the second die defines therein an interior space having a polygonal cross-sectional shape with respect to the direction of die-fastening, the first die is adapted to enter into the interior space of the second die in the direction of die-fastening in the interior space so to press-mold the material in order to form the lens surface while the material is bulged out through gaps between the first die and the second die around the lens surface whereby forming protrusions. An optical element and a mold assembly for an optical element are also provided.

Production method of optical element, optical element forming mold and optical element

A cavity surface-forming plate of a mold for injection-molding a plastic substrate is coarsely polished, and then a surface for defining a cavity is applied with electroless Ni&mdash;P plating. The surface of the plating is polished with abrasive grains to obtain surface roughness of Ra&lE;2.0 nm and Rmax&lE;22 nm. The plastic substrate molded with the mold has smoothness equivalent to the polished plating surface. A concave-convex pattern for forming pits may be formed on the cavity surface. A magnetic disk or an optical disk provided with the substrate makes it possible to realize the near contact system for a magnetic or magneto-optical head. Thus, it is possible to realize high density recording.

Substrate for information recording disk, mold and stamper for injection molding substrate, and method for making stamper, and information recording disk

A cavity surface-forming plate of a mold for injection-molding a plastic substrate is coarsely polished, and then a surface for defining a cavity is applied with electroless Ni-P plating. The surface of the plating is polished with abrasive grains to obtain surface roughness of Ra.ltoreq.2.0 nm and Rmax.ltoreq.22 nm. The plastic substrate molded with the mold has smoothness equivalent to the polished plating surface. A concave-convex pattern for forming pits may be formed on the cavity surface. A magnetic disk or an optical disk provided with the substrate makes it possible to realize the near contact system for a magnetic or magneto-optical head. Thus, it is possible to realize high density recording.

Substrate for information recording disk, mold and stamper for injection

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Fujisawa, Japan

Makoto Aihara