Method of analyzing astigmatic difference and method of correcting the spot diameters for an optical device and spot analysis system

摘要

A method of analyzing the astigmatic difference of an optical device for analyzing the astigmatism inherent to the optical device by utilizing a condensation performance analysis system while correcting the astigmatic difference inherent to the condensation performance analysis system for analyzing the condensation performance of the optical device to be analyzed. The method of analyzing an astigmatic difference has steps comprising: obtaining the astigmatic difference R(theta_n) at an angle theta_n while rotating the data points obtained from the optical device about given basic axes; computing a vector coefficient R₀ in the same direction as the basic axes and another vector coefficient R₄₅ at 45 degree to the basic axes by utilizing the maximum angle theta_max at the greatest value of the astigmatic difference R(theta_n) and the greatest astigmatic difference theta_max; computing an astigmatic difference R(theta) at an arbitrary angle theta derived from the vector coefficient R₀ and the vector coefficient R₄₅ by a fitting technique; correcting the vector coefficient R₀ and the vector coefficient R₄₅ by analyzing the condensation performance analysis system using a reference optical device with a known astigmatic difference; and computing the astigmatic difference of the optical device by utilizing the corrected vector coefficient R₀ and corrected vector coefficient R₄₅.