DIFFRACTION OPTICAL ELEMENT

摘要

An image-capturing optical system including a lens which has a first surface and a second surface and is provided with a diffraction grating disposed only on either the first surface or the second surface. If the diameter of the effective area formed by the light ray of the maximum angle of view incident on the lens on the surface on which the diffraction grating is provided is D, the F number of the maximum angle of view of the image-capturing optical system is Fno, the abbe number of the lens with respect to the d line is ?d, and the F number of the on-axis light pencil is F; the average diffraction ring zone pitch ? of the effective area satisfies the expression below. [Expression 6]