| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of damages such as cracks in tables and rails even in a long time service by forming a stone material of a base board whose coefficient of thermal expansion is smaller than that of the stone forming an upper table, a lower table, upper rail groups and lower rail groups. SOLUTION: Stone material especially excellent in the mechanical strength is selected for the material of a suction table 9, an X-table 10, a supporting table 11, a Y-table 14, and Y-axis rail groups 15, 16 which are components of an XY-table 2. The table 10, 14 the supporting table 11, and the rail groups 15, 16 are difficult to occure damages such as cracks even for a long time service. Because the stone material whose coefficient of thermal expansion is especially small is selected for a block 3 which is a foundation of the device and whose area is large, the expansion and the shrinkage associated with the temperature change are extremely small even for the block 3 of large area. |
