Relief type diffraction optical element, optical system comprising the same and mold for manufacturing the same

摘要

A relief type diffraction optical element including a substrate made of an optical material, said substrate having formed on its surface a non-even width relief pattern which include a first zone group consisting of at least one zone whose cross sectional configuration is formed by a curvilinear portion which follows a phase shift function or at least two rectilinear portions which approximates the phase shift function, and a second zone group consisting of a plurality of zones each having a single rectilinear portion approximating the phase shift function.