Imaging element having plural light collecting parts each including a specific projection and depression structure, method for manufacturing imaging element, pixel design method, and electronic apparatus
View Patent ↗An imaging element includes a plurality of pixels that are two-dimensionally arranged and each have a light receiving part including a photoelectric conversion element and a light collecting part that collects incident light toward the light receiving part. Each of the light collecting parts in the plurality of pixels includes an optical functional layer having, in a surface, a specific projection and depression structure depending on the pixel position.
1. An imaging element comprising:
a plurality of pixels configured to be two-dimensionally arranged and each have
a light receiving part including a photoelectric conversion element and
a light collecting part that collects incident light toward the light receiving part,
each of the light collecting parts in the plurality of pixels including an optical functional layer having, in a surface, a specific projection and depression structure depending on a pixel position.
2. The imaging element according to claim 1 , wherein
the projection and depression structure in the optical functional layer has smaller scale as distance from a center pixel becomes longer in the plurality of pixels.
3. The imaging element according to claim 2 , wherein
an exit angle of a light beam passing through the optical functional layer is substantially constant in the plurality of pixels.
4. The imaging element according to claim 2 , wherein
the scale of the projection and depression structure is smaller than a received-light wavelength in the light receiving part.
5. The imaging element according to claim 1 , wherein
the light collecting part has a lens as the optical functional layer, and
the projection and depression structure is provided in a surface of the lens.
6. The imaging element according to claim 5 , wherein
an inner lens exists between the lens and the light receiving part.
7. The imaging element according to claim 6 , wherein
the projection and depression structure is provided in a surface of the inner lens.
8. The imaging element according to claim 5 , wherein
an antireflection film exists between the lens and the light receiving part.
9. The imaging element according to claim 8 , wherein
the projection and depression structure is provided in a surface of the antireflection film.
10. The imaging element according to claim 5 , wherein
the lens is so disposed as to be shifted toward a center pixel in the plurality of pixels, and
the amount of shift of the lens is larger as distance from the center pixel becomes longer.
11. A method for manufacturing an imaging element, the method comprising:
forming an optical functional layer having, in a surface, a specific projection and depression structure depending on a pixel position in each of light collecting parts in a plurality of pixels, in forming the plurality of pixels that are two-dimensionally arranged and each have a light receiving part including a photoelectric conversion element and the light collecting part that collects incident light toward the light receiving part.
12. The method for manufacturing an imaging element according to claim 11 , wherein
a lens is provided as the optical functional layer, and
the projection and depression structure is formed in a surface of the lens.
13. The method for manufacturing an imaging element according to claim 12 , wherein
the projection and depression structure in the optical functional layer is formed by using a nanoimprint method.
14. The method for manufacturing an imaging element according to claim 12 , wherein
the projection and depression structure in the optical functional layer is formed by using a nanoball solution.
15. The method for manufacturing an imaging element according to claim 12 , wherein
an effective refractive index of the lens is obtained as a function of exit pupil distance and distance from a center pixel, and
scale of the projection and depression structure is decided based on the obtained effective refractive index.
16. A pixel design method used in designing scale of a projection and depression structure in a pixel including an optical functional layer having the projection and depression structure in a surface, the method comprising:
obtaining an effective refractive index of the optical functional layer as a function of exit pupil distance and distance from a center pixel; and
deciding the scale of the projection and depression structure based on the obtained effective refractive index.
17. An electronic apparatus having an imaging element comprising:
a plurality of pixels configured to be two-dimensionally arranged and each have a light receiving part including a photoelectric conversion element and a light collecting part that collects incident light toward the light receiving part,
each of the light collecting parts in the plurality of pixels including an optical functional layer having, in a surface, a specific projection and depression structure depending on a pixel position.