Research on Measuring Path and Surface Fitting Algorithm for Non-axisymmetric Aspheric

In accordance with the requirements and characteristics of non-axisymmetric aspheric surface measuring, three measuring paths were put forward and estimated. The applicant situations of the three paths were also analyzed. A data processing system was created for the measuring of non-axisymmetric aspheric surface. Levenberg-Marquardt method was adopted as the nonlinear least squares to fit the discrete data. The fitting result was assessed by the fitting residuals. The experimental results show that the fitting residuals was in the 10(-3)mm magnitude when convergence index parameter set as 1 x 10(-10) mm. Compared with the theory equation, it's shown that the method can not only be used for non-axisymmetric aspheric surface quality evaluation, but also can generate compensation data to improve machining precision.