| 摘要 |
PROBLEM TO BE SOLVED: To provide an aberration measuring method in which a higher-order astigmatism and a higher-order aberration can be measured at high speed in an optical-system objective lens for an information storage medium of an optical disk system and to provide an aberration evaluation apparatus. SOLUTION: The evaluation method of the lens is provided with a process (a) in which light radiated from the lens is diffracted and in which two beams of diffracted light of different orders are made to interfere so as to obtain a shearing interference figure, a process (b) in which phases of the beams of diffracted light are changed, a process (c) wherein, in the shearing interference figure, the phase of a change in light intensity is found, in a plurality of measuring points, on a line segment which passes the middle point connecting two optical axes of the beams of diffracted light and which is perpendicular to a straight line connecting the two optical axes and a process (d) in which, when positions of the measuring points are designated as s and when the phase is designated asϕ, the phaseϕis approximated by the quartic function or the quintic function of the positions s of the measuring points and in which the the fifth-order coma aberration of the lens is evaluated by the fourth-order factor value of the functions.
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