Patent ID: 6624941
Filing Date: 2003-09-23
Classification: G02B

Abstract:
A diffraction optical element, comprising:a base element; and a diffraction lens structure including a plurality of annular zones concentrically arranged about an optical axis of said base element, minute steps extending in a direction of said optical axis being formed between said plurality of annular zones, said plurality of annular zones being formed on a surface of said base element, wherein said plurality of annular zones include at least one narrow zone satisfying condition (1) and at least one wide zone satisfying condition (2): &Dgr;Z(i)E(i)â€ƒâ€ƒ(1), and &Dgr;Z(i)>(3/2)Â·&Dgr;E(i)â€ƒâ€ƒ(2), wherein, i represents the order of the steps counted from the optical axis, &Dgr;E(i) represents an absolute value of an OPD provided by the i-th step, and &Dgr;Z(i) represents an absolute value of a difference between OPDs provided, with respect to a base curve, by an inner side end portion and outer side end portion of an annular zone between an i-th step and (i+1)-th step.