DIFFRACTION GRATING LENS, DESIGN METHOD FOR OPTICAL SYSTEM HAVING SAME, IMAGE COMPUTATION PROGRAM, AND PRODUCTION METHOD FOR DIFFRACTION GRATING LENS

摘要

This design method for an optical system having a stepped diffraction grating lens (12) includes: a flare computation step for specifying a provisional shape of a diffraction grating surface, and calculating a flare level; and a determination step for deciding whether the flare level lies within a permissible range, and if lying within the permissible range, adopting the provisional shape as the shape of the diffraction grating surface, or if lying outside the permissible range, returning to the flare computation step. The flare computation step has: a provisional shape specification step for specifying a provisional shape; a phase computation step for using the provisional shape to carry out ray tracing, at a predetermined angle, from the object surface to the image surface of the optical system, and calculating phase information; a pupil distribution step for calculating, on the basis of the phase information, a pupil distribution on the exit pupil; and a point image distribution step for using wave propagation analysis to calculate a point image distribution on the image plane from the pupil distribution, and compute the flare level.