Effective method for extracting aspheric parameters inherent in unknown aspheric surfaces

In this paper, we propose an effective method for extracting the important parameters like radius of curvature, conic constant, and deformation coefficients indwelling unknown aspheric surfaces. These parameters can be inversely found from measured data by using the method that is based on aspheric equations and conic surfaces. To demonstrate the precision of the method, it is compared with a higher-order polynomial curve fit, employing two different examples. In a theoretical case, each largest fitting error (or shape error) resulted from the two methods appears a significant difference in precision. Lastly, we apply the proposed method to a real example and show the results.