| 摘要 |
PURPOSE:To obtain a digital signal with a little quantity of error ratio by specifying the combination of the width and depth between the group and the pit of an optical memory element. CONSTITUTION:When the group or pit formed at the substrate of an optical memory element is irradiated by a spot such as a laser, the light is diffracted and a reflecting light quantity is decreased. The intensity (reflecting ratio) D of the reflecting light is changed by the width W and depth (d) of a group. Here, the level of a reflecting light at a part (a) having as pits is approximately one, the width and depth W1, W2, d1 and d2 are set so that the reflecting ratio on a group (b) can be D(W1 and d1), the reflecting ratio on a pit (c) can be D(W2 and d2) and 2D(W1 and d1)=1+D(W2, d2) can be obtained. For the signal obtained from this, an amplitude L1 of the upper half of the signal for a track number and an amplitude L2 of the lower half come to be equal. Namely, the DC level of the part of the group and the DC level of the track number come to be equal and the erroneous digital signals will not be obtained. |
