Patent ID: 7175087

Claim:
A method of analyzing an astigmatic difference of an optical device for analyzing an astigmatism inherent to said optical device by utilizing a condensation performance analysis system while correcting the astigmatic difference inherent to said condensation performance analysis system for analyzing the condensation performance of said optical device to be analyzed; said method of analyzing astigmatic difference has steps comprising: obtaining the astigmatic difference R (θ n ) at an angle θ n while rotating data points obtained from said optical device about given basic axes; computing a vector coefficient (R 0 ) in a same direction as said basic axes and another vector coefficient (R 45 ) at 45 degrees to said basic axes utilizing a maximum angle θ max at the greatest value of said astigmatic difference R(θ n ) and the greatest astigmatic difference (θ max ); computing an astigmatic difference R(θ) at an arbitrary angle θ derived from said vector coefficient Rθ and said vector coefficient R 45 by a fitting technique; correcting said vector coefficient R 0 and said vector coefficient R 45 by analyzing said condensation performance analysis system using a reference optical device that has a known astigmatic difference; and computing the astigmatic difference of said optical device by utilizing a corrected vector coefficient R 0 and a corrected vector coefficient R 45 .