DIFFRACTIVE IMAGING LENS, DIFFRACTIVE IMAGING LENS OPTICAL SYSTEM AND IMAGING DEVICE USING THE DIFFRACTIVE IMAGING LENS OPTICAL SYSTEM

摘要

Provided is a diffractive imaging lens (10) having a surface whereupon a diffraction grating shape is formed. The diffraction grating shape has a plurality of steps concentrically formed with an optical axis (25) at the center. The diffraction grating shape is provided with a first portion wherein step differences (di) between the steps are substantially the same in the diameter direction of the concentric circle, and a second portion outside the first portion with the step differences (di) gradually reduced outward from the optical axis (25). Alternatively, in the diffraction grating shape, the step differences (di) are gradually reduced outward from the optical axis (25) over the entire diffraction grating shape.