| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical system capable of increasing a depth of field by imparting a phase difference corresponding to an angle around an optical axis to passing-light. SOLUTION: The optical system includes a light modulation part for imparting the phase difference corresponding to the angle around the optical axis to the light from an object point, and then, the light from the object point is enlarged to have a nearly fixed size, regardless of a distance up to the object point. The light modulation part is allowed to impart the phase difference which changes monotonously to the angle. The light modulation part is allowed to impart the phase difference which is proportional to the angle. The light modulation part is allowed to impart the phase difference which changes monotonously to the angle to the light passing through each of a plurality of areas separated at different distances from the optical axis, and also, at least any of the plurality of areas in the light modulation part is allowed to impart the phase difference having an angle dependency different from that of the phase difference imparted by other areas, to the passing-light. COPYRIGHT: (C)2010,JPO&INPIT
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