| 摘要 |
PURPOSE:To facilitate detecting undulation and fins of core side faces by forming grooves packed with a glass from a tape slide face to a core lower end face and inclining the bottom face of both end parts in the breadthwise direction of grooves with respect to core side faces. CONSTITUTION:Grooves 3 extended to a core lower end face 2B from a tape slide face 2t are formed on both side faces 2S of a core 2 consisting of two core parts 2a and 2b. Each groove 3 is deep in the center part and is shallow in both end parts in the breadthwise direction, and the groove bottom in the center part is formed into an arcuate surface 3a, and groove bottoms in both end parts 3b are formed into slopes inclined at a small angle theta to the side faces 2S of the core 2. Side faces 2S are sliced after packing the glass in grooves 3 to obtain the core 2. By this constitution, curved parts 8W are formed on boundary lines 8 bteween grooves 3 and side faces 2S to detect an undulation W easily if the undulation W exists. If fins B exist, they are easily detected because the bending state is different.
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