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High-order optical diffraction element e.g. for commercially made objective lens, has annular narrow and broad zones fulfilling calculated first and second conditions to compensate for chromatic aberration
High-order optical diffraction element e.g. for commercially made objective lens, has annular narrow and broad zones fulfilling calculated first and second conditions to compensate for chromatic aberration
A diffraction element has a basic element and a diffraction lens structure . The annular zones of the diffraction lens structure comprise at least one narrow zone and at least one wide zone fulfilling first (1) and second (2) conditions respectively: Delta Z(i) less than (1/2) . Delta E(i).........(1) and Delta Z(i) greater than (3/2) . Delta E(i).........(2), in which i gives the absolute value of the optical path difference from the optical axis, and Delta Z(i) gives the absolute value of the difference between the optical-path differences. An Independent claim is given for an optical lens for an optical load.
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