PURPOSE: To improve the transferability and to reduce the influence upon a reproducing picture signal and to obtain a stable tracking signal by forming a guide groove so that its sectional shape is U-shaped and has no polygonal parts and is smooth.
CONSTITUTION: When a Te-C layer 402 and an Au layer 403 are formed on a glass substrate 401 and laser light 404 is irradiated from the side of the film surface, swellings 405 are formed in laser light irradiated parts by the discharge of gas from the Te-C layer due to the laser light irradiation, and an original disc 406 with guide grooves is produced by continuous irradiation. The shape of formed guide grooves 503 has no polygonal parts and are smooth. Desirablly, a groove width 2A is set to ≥40% of the beam diameter of the laser light (diameter in the position where the intensity is 1/e2 of the intensity in the center) on the guide groove 503, and a maximum depth H of the groove is set to 5W20% of a used laser light eavelength in terms of optical length. Thus, the transferability of the groove shape in each process is improved without the influence upon the reproducing picture signal neither the degradation of a tracking signal output characteristic.
HOSHINO ISAO
MORI AKIFUMI
| JPS5210102A | 1977-01-26 | |||
| JPS5136923A | 1976-03-29 |