Standard

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PROBLEM TO BE SOLVED : To provide a reference device, making correction operation of troublesome dimensions unnecessary even when environmental temperature changes and capable of obtaining an accurate measured value in a permissible range by constituting the device of cordierite ceramic having low coefficient of thermal expansion in a specific temperature range and a young modulus in a specific value or above. SOLUTION : This reference device comprises a block gauge 1, a cylindrical gauge 2, a pin gauge 3, a quadratic prism 4 or the like used as a standard gauge in dimensional measurement. The reference device is prepared from cordierite ceramic having =130 Gpa young modulus. A ceramic consisting mainly of cordierite and containing at least one kind of element selected from yttrium, rare earth elements, 2a group elements and 4b group elements in an amount of 3-15 wt.% expressed in terms of oxide is preferable as the cordierite ceramic. Since the reference device has extremely small thermal expansion and shrinkage to the change of environmental temperature in measurement, correction operation of the reference device is not required.