UNCERTAINTY IN MEASUREMENTS OF DIMENSIONAL CHANGES FROM AN INTERFEROMETRIC DILATOMETER

摘要

The analysis of uncertainty has shown that, V although the dead-path lengths have been reduced to the sample length by the balanced interferometer design, the uncertainty associated with the correction for dead-path error is the most significant source of uncertainty for measurements in air. It is necessary to operate the interferometer in a vacuum chamber in order to achieve the proposed accuracy. Two key components for further improving the measurement accuracy of the interferometer in vacuum are to reduce the nonlinearity resulting from the optical mixing and to improve the stability of laser wavelength. It can be concluded that this double-pass interferometer should be able to measure dimensional changes with an uncertainty of 2 nm (3σ), which meets the accuracy requirement of the interferometric dilatometer.