Abstract: An optical recording medium has spirally or concentrically formed tracks and is capable of an optical recording. The optical recording medium includes a data recording and reproducing area divided into a plurality of zones in the radial direction. One zone is divided into a plurality of sectors respectively having an address part including pits having address information and a data part only composed of grooves. The number of sectors forming each zone is different. An optical disc is formed so that an average reflectance Iadd of the address part and an average reflectance Idata of the data part satisfy a relation expressed by 0.7≦(Iadd/Idata)≦1.3 or 0.8≦(Iadd/Idata)≦1.2.

Abstract: An optical information recording medium, which includes both of a land surface and a groove surface as a recording track and presents high signal quality. The optical information recording medium includes both a land and a groove as the recording track on a substrate, in which a laser light is irradiated from a reverse side of the substrate to thereby carry out a recording and a reproduction, and an inclination angle of a groove side is 25° or more and 40° or less, and both of arithmetic average roughness (Ra) on the land surface and the groove surface are assumed to be 0.2 to 0.7 nm.

Abstract: A recording medium and a recoding medium master, and a method of manufacturing the recording medium which comply with the standard of recording/reproducing characteristic established in the MD standard while enabling precise discrimination of the pit track and groove track and optical detection of the pits by optical pickup and the like are provided. Pits and grooves are arranged on a surface of a disc-shaped substrate so as to form a grooves and the ratio is from 1.00 exclusive to 1.13 inclusive. It is preferable that the track pitch of the grooves is from 1.50 &mgr;m inclusive to 1.70 &mgr;m exclusive. The width of the pits and grooves in the radial direction of the substrate is the same.

Abstract: A recording medium and a recoding medium master, and a method of manufacturing the recording medium which comply with the standard of recording/reproducing characteristic established in the MD standard while enabling precise discrimination of the pit track and groove track and optical detection of the pits by optical pickup and the like are provided. Pits and grooves are arranged on a surface of a disc-shaped substrate so as to form a grooves and the ratio is from 1.00 exclusive to 1.13 inclusive. It is preferable that the track pitch of the grooves is from 1.50 &mgr;m inclusive to 1.70 &mgr;m exclusive. The width of the pits and grooves in the radial direction of the substrate is the same.

Abstract: In an optical recording medium having formed along recording tracks thereon pits indicative of information signal, a ratio Pw/Tp where Pw is the width of the pit and Tp is the pitch of the tracks is within a range of 0.4 to 0.55. The push-pull method or differential push-pull method is adopted for tracking servo control of the optical recording medium.

Abstract: A light exposure device for a master optical disc capable of exposing to light a desired area of the master optical disc to high precision for forming crests and recesses of broad widths therein to high precision. Specifically, the light exposure device for the master optical disc exposes to light the portions of a photoresist coated on a substrate of the optical disc adapted to form a pre-set pattern corresponding to recorded information signals. The light exposure device for the master optical disc includes a light-condensing optical element 15 for condensing the laser light radiated from a light source, a deflecting optical element 16 for wobbling the laser light condensed by the light-condensing optical element 15 and an optical system 17 arranged downstream of the focal point position of the light-condensing optical element 15 for re-imaging the laser light wobbled by the deflecting optical element 16 at a location upstream of the objective lens.

Abstract: An eyepiece lens system comprising, in the order from the side of incidence of rays, a first lens unit having positive or negative refractive power as a whole and a second lens unit having positive refractive power as a whole, said eyepiece lens system having little aberrations, image surface flatness excellent to the marginal portions of visual field, a high eye point and a wide visual field.