| 摘要 |
PURPOSE:To diminish inter-track spacings to about the half value of the diameter of a light spot and to increase a recording density by alternately disposing grooves of different depths so as to incorporate the two grooves within the spot and recording information pits on the plane between grooves. CONSTITUTION:The recessed shallow grooves 24 and the deep grooves 25 are alternately disposed in the direction perpendicular to the progressing direction in such a manner that the two grooves are contained within the light spot on the disk 3 surface consisting of a PbTeFe recording film, etc., on a disk substrate 29. The information pits 36 to 38 are recorded on planes 26 to 28 between the grooves. The depths of the grooves 24, 25 are preferably set at lambda/8, 3lambda/8 and are also preferably set at lambda/8, 2.5lambda/8. The information is preferably reproduced by detecting the change in the intensity of the interference region of zero order and third order on the groove 24 side. |
