A precise algorithm for wavefront fitting using Zernike polynomial is studied which can be applied in the digital wavefront processing. The polynomial coefficients of Zernike can be obtained through solution of overdetermined <b>Ax = W</b> equations by means of Household transformation. Differing from the conventional method of direct constructing normal equation group or the Gram-Schmidt orthogonalization, the new algorithm which utilizing Householder transformation orthogonalizes and triangulate the matrix of overdetermined equations set, and solve the coefficients. It is a healthy fitting algorithm, and computational error which is introduced in the process of constructing normal equation group can be avoided in the new algorithm. It has been proved to be an efficacious algorithm with characteristic of good stability and easy implementation.
The coherent artifacts have harmful influence on the measurement results and make the precision worse during the optical testing. Using RoF illumination method, we can get evener coherent artifacts on the interferogram, improve the gain in S/N ratio, and reduce the measurement error. In this paper we analyze the RoF illumination interferometer, compare the spatial coherence of the RoF and that of the quasi-point light source, get the intensity distribution of the interference field, obtain the fringe visibility, and make a further analysis of the result precision dependence on RoF radius and cavity length.