| 摘要 |
PURPOSE:To simplify a signal reproduction system by optimizing the depth and width of the rugged pits of an address information part and nearly equalizing the signal modulation factors of the address information part and data recording part. CONSTITUTION:Recording of the rugged pits 1 of the address information part and the data recording pits 2 is executed with the phase transition recording film 4 consisting of an Sb-Se-Bi system by changing the same from the crystalline state to the amorphous state. Since the reflectivity of the amorphous state is 20%, 0.7 reproduced output is obtd. with the unrecording part as 1. The signal levels of the address information part and the data recording part can be nearly equalized by specifying the pit depth to 50nm and pit width to 0.4-0.6mum in the address information part when the track pitch is assumed to be 1.6mum, the NA of an objective lens 0.5, the wavelength of reproducing light 830nm and the refractive index of a substrate 1.59 (refractive index of a polycarbonate resin). The common use of two data detecting circuits is possible in this way and the signal reproducing system is simplified. |
