Absolute surface metrology by shear rotation with position error correction

Background: Absolute test is one of the most important and efficient techniques to saperate the reference surface which usually limits the accuracy of test results. Method: For the position error correction in absolute interferometry tests based on rotational and translational shears, the estimation algorithm adopts least-squares technique to eliminate azimuthal errors caused by rotation inaccuracy and the errors of angular orders are compensated with the help of Zernike polynomials fitting by an additional rotation measurement with a suitable selection of rotation angles. Results: Experimental results show that the corrected results with azimuthal errors are very close to those with no errors, compared to the results before correction. Conclusions: It can be seen clearly that the testing errors caused by rotation inaccuracy and alignment errors of the measurements can be consequently eliminated from the differences in measurement results by the proposed method.