Influence of coordinates deviation on parameter fitting in testing off-axis aspherics

Accurate measurement of the vertex radius of off-axis aspheric mirrors is the key to guarantee the assembly and adjustment quality. During the tests of off-axis aspheric mirrors, the influence of coordinates deviation was analyzed in order to improve the precision of fitted results. A fitting model with the corresponding processing method was proposed so that the impact of coordinates deviation could be eliminated. Besides, the parameter fitting procedures were also presented. Compared with the classical direct fitting, presented method can achieve smaller Sum of Square Error and Root of Mean Squared Error while the coefficient of determination is much closer to 1. The experiment verifies the the proposed method's validity. Furthermore, this method is available to coordinates deviation analysis and parameter fitting process in all off-axis aspheric mirror tests.