| 摘要 |
PURPOSE:To improve a signal characteristic such as jitter (swinging or fluctuation of digital signal in time base direction) and block error rate, etc., by setting the values of the depth and the width of a pregroove at specified values. CONSTITUTION:The depth dsub of the pregroove is made over 150nm as its shape, and in addition, its width wsub is made below 0.6mum. Therefore, much light absorptive material comes to be stored in the narrow pregroove 6, and absorbed heat is confined here, and the clear bit 11 of a good edge can be generated. Namely, the heat of a light absorptive layer 3 based on the absorption of the recording laser light L1 is confined in the pregroove 6 as being suppressed in the rate of diffusion to the outside, and a clear deformed part can be formed on the surface of a base plate 2. Thus, recording in which bit width and the edge are well-regulated is executed, and the specification values of the block error rate and the jitter prescribed in a CD standard are satisfied. |
