Method to test rotationally asymmetric surface deviation with high accuracy

We have proposed a new absolute method to test rotationally asymmetric surface deviation. Relying on the high accuracy of Zernike polynomial fitting with least-squares algorithm for the low-frequency component and preserving the high-frequency component with the averaging method, the new method can guarantee the high accuracy of the measurement result with fewer rotational measurements compared to the traditional multiangle averaging method. It realizes a balance between the accuracy and efficiency of the measurements. It has been verified by experiments; the root mean square (rms) of residual figure between the two methods is similar to 0.6 nm. Meanwhile, the new method can suppress environmental noise introduced in measurement results well. (C) 2012 Optical Society of America