Method of analyzing astigmatic difference and method of correcting the spot diameters for an optical device and spot analysis system
View Patent ↗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(θ n ) at an angle θ n while rotating the data points obtained from the optical device about given basic axes; computing a vector coefficient R 0 in the same direction as the basic axes and another vector coefficient R 45 at 45 degree to the basic axes by utilizing the maximum angle θ max at the greatest value of the 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 the vector coefficient R 0 and the vector coefficient R 45 by a fitting technique; correcting the vector coefficient R 0 and the vector coefficient R 45 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 R 0 and corrected vector coefficient R 45 .
1. 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 .
2. The method of correcting a spot diameter obtained by said optical pickup device based on the astigmatic difference, which is computed by said method of analyzing the astigmatic difference as set forth in claim 1 , wherein said optical device is an optical pickup device and said condensation performance analysis system is a spot analysis system which corrects a spot diameter.
3. A spot analysis system which corrects a spot diameter by said method for correcting a spot diameter as set forth in claim 2 .
4. A method for 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 said astigmatic difference has steps comprising:
obtaining said astigmatic difference R (θ n ) at an angle θ while rotating data received 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 by derivation from said vector coefficient R 0 and said vector coefficient R 45 by using a fitting technique;
computing a correction coefficient α 0 and correction intercepts β 0 for said vector coefficient R 0 while computing a correction coefficient α 45 and correction intercepts β 45 for said vector coefficient R 45 by analyzing a reference optical device that has a known astigmatic difference with said condensation performance analysis system;
correcting said vector coefficient R 0 utilizing said correction coefficient α 0 and correction intercepts β 0 and correcting said vector coefficient R 45 utilizing said correction coefficient α 45 and said correction intercept β 45 ; and
computing the astigmatic difference of said optical device utilizing a corrected vector coefficient R 0 and a corrected vector coefficient R 45 .
5. The method of correcting a spot diameter obtained by said optical pickup device based on the astigmatic difference, which is computed by said method of analyzing the astigmatic difference as set forth in claim 4 , wherein said optical device is an optical pickup device and said condensation performance analysis system is a spot analysis system which corrects a spot diameter.
6. A spot analysis system which corrects a spot diameter by said method for correcting a spot diameter as set forth in claim 5 .