Stability of the reference flat used in Fizeau interferometer and its contribution to measurement uncertaint

摘要

Measurement uncertainty is an important topic for traceable measurements. Nevertheless not many literatures on the uncertainty of flatness measurements have been reported. In this paper, we report on this issue according to the Guide to the Expression fo Uncertainty in Measurements (GUM). First stability of the reference optical flat used in Fizeau interferometer is discussed analytically, numerically, and experimentally. Then other uncertainty sources in actual measurements are investigated. As a result the uncertainty of flatness measurement of a large aperture flatness interferometer made by National Metrology Institute of Japan is 1/77 wavelength.