| 摘要 |
PURPOSE:To stabilize the dimension between an element end surface and a reference surface invariably constant by providing an element of thermal expansion reversely from the tip of a main pole stood on the reference surface toward the reference surface, and equalizing the thermally expanded or contacted side of the main pole to that of the element of thermal expansion. CONSTITUTION:On a reference surface 1, a main pole 2 with length L is stood and at the top of it, a base 3 is fixed in parallel to the reference surface. On the reverse surface of the base, an element 4 of thermal expansion with length l is fitted, and on the end surface 5 of the element 4, a supporting plate 7 energized toward the base side by springs 6 is fitted. Then, the thermally expanded or contacted size of the main pole 2 is equalized to that of the element 4 of thermal expansion. Consequently, the height H from the reference surface to the supporting plate 7 is held constant regardless of fluctuations of temperature. |
