Diffraction optical element

TL;DR: In this article, a diffraction optical element which is easily manufactured and reduced in the wavelength dependency of diffraction efficiency and can effectively prevent a flare, a ghost, etc., from being generated.

Abstract: PROBLEM TO BE SOLVED: To provide the diffraction optical element which is easily manufacture and reduced in the wavelength dependency of diffraction efficiency and can effectively prevent a flare, a ghost, etc., from being generated. SOLUTION: This element has 1st, 2nd, 3rd, and 4th areas 11, 12, 13, and 14 which are laminated sequentially in contact or closely, a 1st relief pattern 21 which is formed on the boundary surface between the 1st and 2nd areas 11 and 12, and a 2nd relief pattern 22 which is formed on the boundary surface between the 3rd and 4th areas 13 and 14; and the 1st, 2nd, 3rd, and 4th areas 11, 12, 13, and 14 are formed of at least three kinds of material which are at least substantially transparent to the wavelength of light in use while the 1st area 11 and 2nd area 12, and 3rd area 13 and 4th area 14 are formed of mutually different materials. The 1st and 2nd relief patterns 21 and 22 have substantially equal pitch distributions and mutually different groove depths, and their corresponding parts are arranged close to each other. COPYRIGHT: (C)1997,JPO