Olympus Optical Company, Ltd.

Jun Kanehira

Naoyuki Ueno

Toshiyuki Kanno

Yasuji Nagata

Seiji Kondo

Hideshi Takahashi

Yoshiko Uematsu

A recording film of a recording medium has tracks with a track pitch of 1.6 .mu.m. Each track has a land and a groove, and the width of each of the land and groove is about 0.8 .mu.m. The groove and land differ relatively in height by a degree corresponding to (2n-1)/4 (n: a natural number) times the wavelength of the irradiated beam. At the time of reproduction, reflected diffraction beam components reflected from the land and groove are provided with a phase difference .pi.. Thus, a peak of the diffraction beam is concentrated within the range of the NA of an objective lens, with high intensity. As a result, the presence/absence of pits located at a distance less than a diffraction limit, which have not been detected in the prior art, can be detected.

Optical recording medium having grooves and lands and/or plural pit

According to the present invention, recording laser beam is shot from a semiconductor laser to form a mark set which comprises a pair of marks on the track of an optical recording medium in the track width direction thereof and first information which has been coded corresponding to the interval between the paired marks in the mark set is recorded on the track of the optical recording medium. At the same time, the plural mark sets are formed on the track of the optical recording medium in the track length direction thereof and second information which has been coded corresponding to the interval between these mark sets is recorded on the track of the optical recording medium. The track of the optical recording medium is scanned in the track width direction thereof with reproducing laser beam shot from a semiconductor laser and .+-. first-order diffraction beam of an optical interference pattern which is created from the paired marks in the mark set thus scanned is detected to reproduce the first information. At the same time, the track is scanned in the track length direction thereof with the reproducing laser beam and zero-order diffraction beam of an optical interference pattern which changes corresponding to the interval between the plural mark sets thus scanned is detected to reproduce the second information.

Optical recording and reproducing method and apparatus for the same

An optical recording medium such as an optical disk, which is capable of reversibly repeating a recording/erasing cycle. This optical recording medium comprises a transparent substrate and recording layer formed on the substrate. This recording layer comprise a liquid crystalline high polymer having side chains and a dyestuff having a recording-light absorbing property. The side chain may preferably comprises mesogen group, a monocyclic or polycyclic compound such as phenyl, benzyl, naphthyl or anthryl group, and alkyl or aryl group having 1 to 18 carbon atoms.

Optical recording medium

An amorphous magnetic alloy having the formula Co.sub.x M.sub.y B.sub.z wherein M is zirconium, hafnium and/or titanium. When M is hafnium or zirconium 70.ltoreq.x.ltoreq.80, 8.ltoreq.y.ltoreq.15 and 10.ltoreq.z.ltoreq.16. When M is titanium, 70.ltoreq.x.ltoreq.72, 16.ltoreq.y.ltoreq.25 and 4.ltoreq.z.ltoreq.10. When M is hafnium together with titanium and/or zirconium, 70.ltoreq.x.ltoreq.80, 8.ltoreq.y.ltoreq.20 and 5.ltoreq.z.ltoreq.16.

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Tokyo, Japan

Jun Kanehira