| 摘要 |
PURPOSE:To obtain stable rotational performance by providing a balance mark on each disk substrate to be used for the top and back surfaces, and sticking the disk substrates in a manner that the balance marks are disposed 180 degree apart from each other. CONSTITUTION:Fine projections and recesses are transferred to the surfaces of disk substrates 1, 2, on which aluminum reflecting films are formed by vapor deposition to form signal areas 11, 21, and further protective coating films 12, 22 are formed thereon. A balance mark 4 is provides at the distance R1 from the center hole of the substrate 1 to be used as the top surface, while a balance mark 5 is provided at the distance R2 from the center hole of the substrate 2 to be used as the back surface, so that each marks can be visually identified. Then substrates 1, 2 are stuck together in a manner that the balance marks 4, 5 are apart from each other by 180 degree and can be visually checked from outside. Thereby, the obtd. medium has stable rotational performance. |
