| 摘要 |
PURPOSE:To prolong the life of the blade of a diamond tool and to process the groove low in noise level over a long distance by specifying the roundness radius of the cutting edge of the blade of the diamond tool. CONSTITUTION:In any diamond tool of a blade width, when a roundness radius (r) of a cutting edge is 0.1mum or above, the blade is not damaged. The larger the roundness radius (r) of the cutting edge of the diamond tool is, the harder the damage of the tool cutting edge occurs, and in proportion to the size of the roundness radius (r) of the cutting edge, the return is easy to occur at the edge part of the groove. As the return of the edge part of the groove comes to be larger, the inclination that the recording reproducing characteristic is worsened is shown. Thus, since the roundness radius (r) of the cutting edge of the diamond tool is 0.1-0.2mum, then, the groove of the low noise level can be formed over the long distance, the optical disk master disk with large diameter can be processed.
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