Abstract
In this paper, the two-orientation method is applied to the measurement of cross-sectional profiles along concentric circles on a spherical test surface using an interferometer. The influence of form errors along concentric circles on the reference surface of the interferometer can be removed by the combination of the measurement data before and after a rotation operation. Furthermore, the differential output is Fourier transformed and the cross-sectional profiles along concentric circles on the test surface are determined by a phase operation. The influence of random errors of sampling in the interferometer output data and that of the positioning error of angular displacement when rotating the test surface are investigated through simulation. Experimental results using a Fizeau type interferometer (ZyGo GPI-XP) that confirm the effectiveness of this method in improving measurement accuracy are also presented.
