Provided is an optical medium reproducing apparatus including: a detection unit that divides a luminous flux into a plurality of regions including a first region and a second region which are different in a position in a radial direction and/or a tangential direction, and combines a plurality of detection signals in correspondence with the amount of light that is incident to each of the plurality of regions with combination patterns which are selected to form signals of a plurality of channels; a multi-input equalizer unit that includes a plurality of equalizer units to which the signals of the plurality of channels are respectively supplied, computes outputs of the plurality of equalizer units, and outputs the resultant value as an equalization signal; and a binarization unit that performs binarization processing with respect to the equalization signal to obtain binary data. An addition signal channel including a constant multiplication of detection signals of the first region and the second region is included in at least one of the combination patterns.

There is provided an optical recording medium substrate including a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25 C. is in a range from 1.1930 g/cm.sup.3 to 1.2000 g/cm.sup.3.

A method is provided for making stamper plates for an embossing drum for embossing tape media. At least one first stamper plate is formed using a master template. The at least one first stamper plate includes first land and groove patterns that are an inverse of the master template land and groove patterns. At least one second stamper plate is formed from the at least one first stamper plate. The at least one second stamper plate includes second land and groove patterns that are an inverse of the first land and groove patterns. Furthermore, the first stamper plates and the second stamper plates have four sections arranged in a travel direction of the tape media, a first and a fourth of the four sections having land and groove patterns that are laterally mirrored with respect to each other. A first stamper plate is coupled to a second stamper plate to form part of the drum for embossing tape media.

A method is provided for making stamper plates for an embossing drum for embossing tape media. The stamper plates include at least one first plate having first land and groove patterns and at least one second plate having second land and groove patterns that are an inverse of the first land and groove patterns. Furthermore, the first stamper plates and the second stamper plates have four sections arranged in a travel direction of the tape media, a first and a fourth of the four sections having land and groove patterns that are laterally mirrored with respect to each other.

There is provided an optical recording medium substrate including a polycarbonate in which an average molecular weight is in a range from 15000 to 16000, and mass per unit volume at 25? C. is in a range from 1.1930 g/cm.sup.3 to 1.2000 g/cm.sup.3.

A method is provided for making an embossing drum that is useable to emboss tape media. The method includes assembling together multiple stamper plates that each have embossing features for embossing tape media, and the stamper plates include at least one first plate and at least one second plate. Furthermore, the embossing features of each first plate are inverted with respect to the embossing features of each second plate.

An ultrasonic molding device for molding thin-walled optical components which includes an ultrasonic assembly and a plunger assembly for melting thermoplastic material and injecting it into a mold under reduced pressure conditions.

A holographic storage layer includes a reflective structure and photosensitive units. The reflective structure is a grid-shaped structure and includes cavities. The photosensitive units are disposed in the cavities, in which each of the photosensitive units is surrounded by the reflective structure. First openings and second openings are defined by the reflective structure, and the photosensitive units are exposed by the first openings and the second openings respectively.

Method for manufacturing an optical information recording medium includes: preparing a substrate material where a first guide groove has been formed on a first side of the substrate material; forming a second guide groove by applying an energy-curable resin material between a second side of the substrate material opposite to the first side and a stamper and subsequently curing the energy-curable resin material to form a substrate; providing at least one recording layer and a cover layer on a first side of the substrate where the first guide groove has been formed, while holding the substrate with the stamper left unremoved from the substrate to protect the second guide groove; and exposing the second guide groove by removing the stamper and providing at least one recording layer and a cover layer on a second side of the substrate where the second guide groove has been formed.

A holographic storage layer includes a reflective structure and photosensitive units. The reflective structure is a grid-shaped structure and includes cavities. The photosensitive units are disposed in the cavities, in which each of the photosensitive units is surrounded by the reflective structure. First openings and second openings are defined by the reflective structure, and the photosensitive units are exposed by the first openings and the second openings respectively.