| 摘要 |
PURPOSE:To equalize the pitch of a disk between the inner peripheral part and inner peripheral part by making a successively laminated recording layer constant in thickness and decreasing the thickness of a highly heat-conductive layer from the inner periphery to the outer periphery. CONSTITUTION:Rectangular recording laser light 5a or step-shaped recording laser light 5b is projected on the optical disk which rotates at a constant rotating speed through a lens 4. The optical disk consists of a transparent substrate 1, the recording layer 2, and the highly heat-conductive layer 3. When information is recorded with the recording laser light 5, the linear speed is low at the inner peripheral part, so its temperature rises as compared with the outer peripheral part. For the purpose, the highly heat-conductive layer 3 having high heat conductivity like metal is made thick at the inner peripheral part and then heat conducted from the recording layer 2 to the highly heat-conductive layer 3 is large in value at the inner peripheral part, so the inner peripheral part and outer peripheral part become equal in temperature. The temperature when the step-shaped laser light 5b is used is a little bit lower than that when the rectangular laser light 5a is used, so the precision of pit size is improved. |
