Dual layer pixel lens for low light cameras
An image sensor for low light cameras including a plurality of image pixels, each including: a photodiode layer; an oxide layer; a metal layer; a first microlens layer for focusing an incident light onto the photodiode layer; and a second microlens layer formed on top of the first microlens layer for generating a collimated light from a sharp-angled light from a low light camera and illuminating said collimated light to the first microlens layer to be focused on the photodiode layer.
1. An image sensor for low light cameras comprising:
a plurality of image pixels, each image pixel comprising:
a photodiode layer;
an oxide layer;
a metal layer;
a first microlens layer for focusing an incident light onto the photodiode layer; and
a second microlens layer formed directly on top of the first microlens layer for generating a collimated light from a sharp-angled light from a low light camera and illuminating said collimated light to the first microlens layer to be focused on the photodiode layer.
2. The image sensor of claim 1 , wherein the second microlens layer is a convex lens layer.
3. The image sensor of claim 1 , wherein the second microlens layer is a concave lens layer.
4. The image sensor of claim 1 , wherein the second microlens layer is a combination of a convex lens layer and a concave lens layer.
5. The image sensor of claim 1 , wherein the second microlens layer is formed on the first microlens layer by optical lithography and thermal reflow process.
6. The image sensor of claim 1 , further comprising a filter layer formed under the first microlens layer.
7. The image sensor of claim 1 , wherein the plurality of image pixels are fabricated with a front side illumination process.
8. The image sensor of claim 1 , wherein the plurality of image pixels are fabricated with a back side illumination process.
9. The image sensor of claim 1 , wherein the oxide layer includes a light guide.
10. The image pixel of claim 9 , wherein the plurality of image pixels are fabricated with a front side illumination process.
11. The image pixel of claim 9 , wherein the plurality of image pixels are fabricated with a back side illumination process.
12. The image sensor of claim 1 , wherein the second microlens layer is formed over the first microlens layer in a shifted position on a lateral axis with respect to the photodiode layer.
13. An image pixel comprising:
a photodiode layer;
an oxide layer;
a metal layer;
a first microlens layer for focusing an incident light onto the photodiode layer; and
a second microlens layer formed directly on top of the first microlens layer for generating a collimated light from a sharp-angled light from a low light camera and illuminating said collimated light to the first microlens layer to be focused on the photodiode layer.
14. The image pixel of claim 13 , wherein the second microlens layer is a convex lens layer.
15. The image pixel of claim 13 , wherein the second microlens layer is a concave lens layer.
16. The image sensor of claim 13 , wherein the second microlens layer is a combination of a convex lens layer and a concave lens layer.
17. The image pixel of claim 13 , wherein the second microlens layer is formed on the first microlens layer by optical lithography and thermal reflow process.
18. The image pixel of claim 13 , further comprising a filter layer formed under the first microlens layer.
19. The image sensor of claim 13 , wherein the second microlens layer is formed over the first microlens layer in a shifted position on a lateral axis with respect to the photodiode layer.