Imaging systems with baffle grids
An imaging system may include a camera module with an image sensor having an array of image sensor pixels. The image sensor may include a substrate having an array of photodiodes, an array of microlenses formed over the array of photodiodes, and an array of color filter elements interposed between the array of microlenses and the array of photodiodes. A grid of baffles may be formed over the array of image pixels and may be configured to block stray light from striking the image pixels. The baffles may extend above the microlens array and may be tilted at an angle with respect to the optical axis of the image sensor. The angle at which each baffle is tilted may be proportional to the chief ray angle of an associated microlens. Baffles may be formed from a light-blocking material such as metal, photoresist, carbon, graphite, or other suitable material.
1. An image sensor having an array of image pixels, comprising:
a substrate;
an array of photodiodes formed in the substrate;
an array of microlenses formed over the array of photodiodes;
an array of color filter elements interposed between the array of microlenses and the array of photodiodes;
a grid of baffles that extend above the array of microlenses, wherein the grid of baffles is configured to block stray light from reaching the array of image pixels; and
a material formed over the array of microlenses, wherein the material has a planar surface and wherein the baffles are formed on the planar surface.
2. The image sensor defined in claim 1 wherein the image sensor has an optical axis and wherein each baffle is tilted at an angle with respect to the optical axis of the image sensor.
3. The image sensor defined in claim 1 wherein the baffles comprise metal.
4. The image sensor defined in claim 1 wherein the baffles comprise photoresist material.
5. The image sensor defined in claim 1 further comprising a grid of color filter barriers, wherein each color filter barrier is interposed between a respective pair of the color filter elements, and wherein each baffle extends from one of the color filter barriers.
6. The image sensor defined in claim 1 wherein the array of image pixels has an associated pixel pitch, and wherein a spacing between adjacent baffles in the grid of baffles is an integer multiple of the pixel pitch.
7. The image sensor defined in claim 2 wherein each microlens is associated with a chief ray angle and wherein the angle at which the baffles are tilted is based on the chief ray angle of an associated microlens.
8. The image sensor defined in claim 2 wherein the array of image pixels has a center and an edge and wherein the angle at which the baffles are tilted with respect to the optical axis increases from the center to the edge.
9. The image sensor defined in claim 8 wherein at least one of the baffles is located at the center of the pixel array and wherein the angle at which the at least one baffle is tilted with respect to the optical axis is zero degrees.
10. An image sensor having an associated optical axis, comprising:
an image pixel array, wherein the image pixel array has a plurality of microlenses and wherein each microlens is associated with a chief ray angle; and
a grid of light-blocking structures on the image pixel array that extend above the microlenses, wherein each light-blocking structure is tilted over an associated microlens at an angle with respect to the optical axis of the image sensor and wherein the angle at which each light-blocking structure is tilted is proportional to the chief ray angle of the associated microlens.
11. The image sensor defined in claim 10 wherein the light-blocking structures comprise a material selected from the group consisting of: metal, photoresist, carbon, and graphite.
12. The image sensor defined in claim 10 wherein the image pixel array has a center and an edge, and wherein the angle at which the light-blocking structures are tilted with respect to the optical axis increases from the center to the edge.
13. The image sensor defined in claim 10 wherein the light-blocking structures have respective lower surfaces, wherein the microlenses have respective lower surfaces, and wherein the lower surfaces of the light-blocking structures are coplanar with the lower surfaces of the microlenses.
14. The image sensor defined in claim 10 wherein at least some of the light-blocking structures have light-disrupting features to block stray light from reaching the image pixel array.
15. The image sensor defined in claim 14 wherein the light-disrupting features comprise roughened surfaces.
16. A system, comprising:
a central processing unit;
memory;
input-output circuitry; and
an imaging device, wherein the imaging device comprises an image sensor having an array of image pixels and wherein the image sensor comprises:
a substrate;
an array of photodiodes formed in the substrate;
an array of microlenses formed over the array of photodiodes;
an array of color filter elements interposed between the array of microlenses and the array of photodiodes; and
a grid of baffles that extend above the array of microlenses, wherein the grid of baffles is configured to block stray light from reaching the array of image pixels, wherein at least some of the baffles in the grid of baffles have light disrupting features to block stray light from reaching the array of image pixels, and wherein the light-disrupting features comprise roughened surfaces.
17. The system defined in claim 16 wherein the image sensor has an optical axis and wherein each baffle is tilted at an angle with respect to the optical axis of the image sensor.
18. The system defined in claim 16 wherein the baffles comprise a material selected from the group consisting of: metal, photoresist, carbon, and graphite.
19. The system defined in claim 17 wherein the array of image pixels has a center and an edge and wherein the angle at which the baffles are tilted with respect to the optical axis increases from the center to the edge.