DIFFRACTIVE OPTICAL ELEMENT AND IMAGING APPARATUS USING THE SAME

1 . A diffractive optical element, comprising

a diffractive surface,

wherein

raised portions and recessed portions are alternately arranged on the diffractive surface, and

a shape of valley bottoms of the recessed portions varies according to regions of the diffractive surface.

2 . The diffractive optical element of claim 1 , wherein

the shape of the valley bottoms of the recessed portions in a central region of the diffractive surface is different from that in an outer region located outside the central region.

3 . The diffractive optical element of claim 2 , wherein

each of the valley portions of the recessed portions is formed to have a chamfered shape, and

an extent of chamfering of the valley portions in the outer region is larger than that in the central region.

4 . The diffractive optical element of claim 2 , wherein

each of the valley portions of the recessed portions is formed to have a chamfered shape, and

an extent of chamfering of the valley portions in the central region is larger than that in the outer region.

5 . The diffractive optical element of claim 1 , wherein

a depth of the recessed portions varies according to regions in the diffractive surface, and

the shape of the valley portions in a region in which the depth of the recessed portions is large is different from that in a region in which the depth of the recessed portions is small.

6 . The diffractive optical element of claim 5 , wherein

each of the valley portions of the recessed portions is formed to have a chamfered shape, and

an extent of chamfering of the valley portions in the region in which the depth of the recessed portions is large is larger than that in the region in which the depth of the recessed portions is small.

7 . An imaging apparatus, comprising:

the diffractive optical element of claim 1 .