| 摘要 |
PROBLEM TO BE SOLVED: To provide a diffraction optical element which has both of an ideal imaging characteristic and an ideal efficiency characteristic, and is independent of a surface profile of a substrate. SOLUTION: In an approximate surface profile consisting of an elliptic plane group, a concept of the surface profile of the substrate does not exist in principle, but in manufacture, a substrate with an approximate surface profile is processed. A luminous flux made incident from an incident point S1 goes to an exit point S2 via each elliptic planes. If an inclination factor in an arbitrary place of each spheroidal surface is the same, and if a solid angle of each luminous flux projected on each elliptic surface from the incident point S1 is the same, an amplitude of each luminous flux becomes the same at the exit point S2 of each flux. When the amplitudes of the luminous fluxes via 8 pieces of spheroidal surfaces 1 to 8 are expressed by complex numbers at the exit point S2, and if they are in phase, they strengthen each other, but if they are out of phase, they weaken each other. Since the strength is the square of an amplitude, the strength becomes very high if the wavelengths are in phase, but the strength becomes small if the wavelengths are out of phase, and a function as a dispersive element is high. COPYRIGHT: (C)2006,JPO&NCIPI
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