| 摘要 |
PROBLEM TO BE SOLVED: To attain a novel depth of focus extension imaging optical system that includes a depth of focus extension element.SOLUTION: A depth of focus extension imaging optical system 202 has a depth of focus extension element 203 added, in which the depth of focus extension element 203 has an aspherical surface shape rotationally symmetrical around an optical axis of the imaging optical system. In the aspherical surface shape, its sag amount:Z varies like at least negative/positive/negative, or positive/negative/positive as a distance from the optical axis increases. In a range:0<|t|<0.4 of a normalization radius:|t| having a radius of the aspherical surface normalized, a maximum value of |dZ/dt| is equal to or more than 0.4, and in more than one part with a range of 0.4≤|t|<0.8, dZ/dt=0.SELECTED DRAWING: Figure 1 |
