Optical element and imaging device

1. An optical element comprising:

a transparent electrolyte layer;

a pair of solid electrochromic layers constituted by a reduction coloring-type solid electrochromic layer and an oxidation coloring-type solid electrochromic layer opposing each other, sandwiching the transparent electrolyte layer; and

a pair of transparent conductive films which sandwiches a pair of the solid electrochromic layers,

the optical element having an apodized characteristic having transmittance gradually increasing from an outer periphery toward a center in a plane orthogonal to a thickness direction of the transparent electrolyte layer.

2. The optical element according to claim 1 , wherein the transmittance in the apodized characteristic in a same distance from the center of the optical element becomes substantially same.

3. The optical element according to claim 1 , further comprising:

a transparent substrate on at least one film of the pair of transparent conductive films.

4. The optical element according to claim 1 , further comprising:

a shielding layer at least one of: between the transparent electrolyte layer and the reduction coloring-type solid electrochromic layer; and between the transparent electrolyte layer and the oxidation coloring-type solid electrochromic layer.

5. The optical element according to claim 1 , wherein a contour of an area in the plane where the transmittance with respect to light of a wavelength of 632 nm becomes 80% or more is concentrically variable by controlling a voltage which is applied between a pair of the transparent conductive films.

6. The optical element according to claim 1 , wherein the area in the plane where the transmittance with respect to the light of the wavelength of 632 nm becomes 80% or more is filled in an entire area by setting the voltage which is applied between a pair of the transparent conductive films to a predetermined value.

7. The optical element according to claim 1 , wherein an area in the plane where the transmittance with respect to the light of the wavelength of 632 nm becomes 10% or less is filled in the entire area by setting the voltage which is applied between a pair of the transparent conductive films to a predetermined value.

8. The optical element according to claim 1 , wherein when the center of the optical element is set as a base point (x=0), a transmittance distribution is substantially given by a Gaussian function represented by

f ( x )=exp(− x 2 /(2σ 2 )).

9. The optical element according to claim 1 , wherein when maximum transmittance with respect to light in a range of wavelengths of 430 nm to 660 nm is set to Tmax 430 to 660 ,

both of transmittance T 430 with respect to light of a wavelength of 430 nm and transmittance T 660 with respect to light of a wavelength of 660 nm in Tmax 430 to 660 =50% satisfy 40% or more.

10. The optical element according to claim 1 ,

wherein in a cross section in a thickness direction which includes the center,

at least one of a shape of the reduction coloring-type solid electrochromic layer and a shape of the oxidation coloring-type solid electrochromic layer is a plano-concave shape, and

a shape of the transparent electrolyte layer is a plano-convex shape or a biconvex shape.

11. The optical element according to claim 1 , wherein the transparent electrolyte layer has a liquid-state material.

12. The optical element according to claim 11 , wherein the liquid-state material has Li.

13. An imaging device comprising:

an image sensor configured to be incidented light from a subject or a light source;

a lens which is disposed between the subject or the light source and the image sensor; and

the optical element according to claim 1 which is disposed between the subject or the light source and the image sensor.