Interference Techniques for Measuring the Surface Profile of Extended Samples

Two interference techniques for measuring the surface profile of extended samples from 60 to 200 mm in length have been developed. The profile is reconstructed by gluing separate frames taken with overlapping. It has been found that the angular reproducibility of the reconstructed profile in both techniques is less than 10 μrad, which corresponds to a profile height difference of about 10 nm. When measuring surfaces with curvature radii R > 1 m, it is recommended to use the stitching technique on a Zygo Verifire 4 highly coherent interferometer, which provides a complete surface map. For surfaces with curvature radii R < 1 m, only the stitching technique on a SuperView W1 white light interferometer is suitable. For particularly important measurements, it is advisable to use both methods to achieve maximum measurement accuracy. The results of the study confirm the effectiveness of the proposed approaches in the field of interference metrological control.