| 摘要 |
PROBLEM TO BE SOLVED: To provide a diffraction optical element which generates diffracted light of high intensity without changing an optical system and without increasing the height h of concaves and convexes of a grid even when the cycleΛof the concave and convexe parts is short and improves the wavelength dependence of incident light. SOLUTION: This diffraction optical element is equipped with a substrate part 30 and the concaves and convexes part 40 of an almost sawtooth-shaped cross section. When design wavelength is defined asλand the refractive index of a peripheral medium is defined as n', the cycleΛof the concaves and convexes part 40 is within the range shown byλ/n'<Λ≤10λ/n' formula 1. When the height and the refractive index of the concaves and convexes part is defined as h and n respectively and the order of diffraction is defined as m, the height h of concaves and convexes of the concaves and convexes part is within the range shown by 0<h≤¾m¾λ/¾n-n'¾. The concaves and convexes part 40 is provided with a convex part 50 at a vertex, a concave part 51 at the lowest point, and a concave bent part 52 and a convex bent part 53 which smoothly continue on an inclination surface 40a between the parts 50 and 51. COPYRIGHT: (C)2004,JPO
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