Double lamination optical data carrier and it commutes use of medium

摘要

The emission beam which 400 or has the wave length of 410nm and was focused (29) with double lamination optical data carrier for the reading out which utilizes with 0.84 or 0.86 numerical apertures (20) is explained. As for the aforementioned medium, baseplate 21 and, the 1st lamination which is named L0 which possesses 1st information layer (22), and the 2nd lamination which is named L1 which possesses 2nd information layer (23) with it has. The emission beam (29) transmitted spacer layer (24), exists with L0 and L1. TS0 which has thickness d _TS0 and effective refractive index n _TS0 and the transmission lamination which is named L0 and medium (20) the entrance place (26) with includes all layers between. TS1 which has thickness d _TS1 and effective refractive index n _TS1 and the transmission lamination which is named L1 and the entrance place (26) with includes all layers between. Spacer layer (24), it has the thickness which is selected from the range of 20 or 30 millimicrons. As for the thickness d _{TS0 which} depends on refractive index n _TS0, and the thickness d _{TS1 which} depends on refractive index n _TS0, it is inside the specified area. This way, both reliability of the respective aforementioned 1st information layer and the aforementioned 2nd information layer of L0 and L1 high read-out is achieved.