| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the azimuth dependency of the power on the whole and to correct the primary spherical aberration (on-axis spherical aberration) by allowing the power values of 1st, 2nd, and 3rd partial systems having an off-Axial curved surface at an arbitrary azimuth angle to meet specific conditions. SOLUTION: The optical system has three partial systems, i.e., a 1st partial system and a 2nd partial system having an off-Axial curved surface and a 3rd partial system having an off-Axial curved surface and the light beam from a subject passes through those three partial system. Then the conditional expression is satisfied, where the path of a light beam exiting from the subject, passing through the center of a stop, and reaching the center of a final image plane is regarded as a reference axis, and e1 is the converted principal point interval between the 1st and 2nd partial system, e2 is the converted principal point interval between the 2nd and 3rd partial systems, andϕ2(ε) is the power at an arbitrary azimuth angle of the 2nd partial system. Further, the conditional expression II is satisfied, whereϕ1(ε) andϕ3(ε) are the power values of the 1st and 3d partial systems at an arbitrary azimuth angle.
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