| 摘要 |
A mark having a length nT (n being an integer equal to or greater than 3 and T being a clock period) is formed by modulating irradiation laser power with three values of recording power Pw, erase power Pe, and bias power Pb (Pw>Pe>Pb). Constant strength periods (At) of the recording power Pw are set as AtT, A1T, . . . , and AmT and constant strength periods (Bt) of the bias power Pb are set as BtT, B1T, . . . , BmT, and CT (C=−1 to 3). The application of laser is divided into pulses in order of AtT, BtT, A1T, B1T, . . . , AmT, BmT, and CT (m=(n−k)/2, k=3 (if n is an odd number), or k=4 (if n is an even number)). (Here, the constant strength period of the recording power Pw for n=3, n=4, n≧5 (odd number), and n≧6 (even number) is set as At3, At4, Atod, and Atev, the constant strength period of the bias power Pb for n=3, n=4, n≧5 (odd number), and n≧6 (even number) is set as Bt3, Bt4, Btod, and Btev, and then, At3+Bt3=Atod+Btod=Am+Bm=2T and At4+Bt4=Atev+Btev=3T). |
