2方位法と半径方向シフト法とを用いた平面度の高精度測定

抄録

A study is presented of a high precision measuring method of flat form errors by combining two-orientation method and radial shift method, when a laser interferometer is applied. The method can remove the measuring errors due to the form errors of the reference surface. In the two-orientation method, two sets of data measured before and after a rotation of the specimen are translated from orthogonal array into polar coordinates expressions. Then the differences between the two are Fourier transformed and the true form errors along the concentric circles are determined by phase operation. In the radial shift method, the differences between two sets of data measured before and after a radial shift are calculated along the radius. Then the true radial straightness errors are determined through polynomial approximation and least square method. Finally the true flat form errors can be obtained by combining both results. It has been ascertained by experiments that the measuring errors are within several nanometers which is comparable with the repeatability of the interferometer.