Micro-lenses for CMOS imagers and method for manufacturing micro-lenses

1. An imaging system comprising:

an imager comprising:

an array of pixel cells;

a micro-lens array positioned over the array of pixel cells, the micro-lens array comprising a plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses, wherein the micro-lens array is formed in a substrate positioned over the array of pixel cells, wherein the micro-lens array comprises lens material; and

a plurality of openings in the substrate, wherein each opening contains lens material that forms a respective plurality of given micro-lenses out of the plurality of micro-lens in the micro-lens array, each of the given micro-lenses having a respective focal point.

2. The system of claim 1 , wherein the micro-lenses are shaped such that the micro-lenses correct for optical aberrations.

3. The system of claim 1 , wherein the lens material exhibits a refractive index greater than that of the substrate.

4. The system of claim 1 , wherein the lens material exhibits a refractive index less than the substrate.

5. The system of claim 1 , wherein the focal point of at least one of the plurality of given micro-lenses differs from the focal point of at least one other of the plurality of given micro-lenses in the same opening.

6. The system of claim 1 , wherein the focal points of the plurality of micro-lenses change gradually across the micro-lens array.

7. The system of claim 1 , wherein each pixel cell comprises a photosensor and wherein each micro-lens is respectively associated with the photosensor of one of the array of pixel cells.

8. The system of claim 1 , wherein at least one of the plurality of micro-lenses has a different shape than another one of the plurality of micro-lenses.

9. The system of claim 1 , wherein at least one of the plurality of micro-lenses has a different size than another one of the plurality of micro-lenses.

10. The system of claim 1 , wherein at least one of the plurality of micro-lenses has a different profile than another one of the plurality of micro-lenses.

11. An imaging system comprising:

an imager comprising:

an array of pixel cells; and

a micro-lens array positioned over the array of pixel cells, the micro-lens array comprising a plurality of micro-lenses, each of the micro-lenses having a respective focal point, wherein the focal point of at least one of the plurality of micro-lenses differs from the focal point of at least one other of the plurality of micro-lenses, and wherein the differing focal points of the plurality of micro-lenses focus light to different depths in the pixel cells.

12. A system comprising:

a processor; and

an imaging device, the imaging device comprising:

a plurality of pixel cells each having a photosensor, wherein each pixel cell has a center; and

a micro-lens array including a plurality of micro-lenses each associated with one of said pixel cells, each micro-lens having a focal point, wherein the focal point of at least a first microlens is shifted, by a first distance, away from the center of the pixel cell associated with the first micro-lens.

13. The system of claim 12 , further comprising a light shield for directing electromagnetic radiation to each photosensor.

14. The system of claim 12 , wherein the micro-lens array includes at least one non-symmetrical micro-lens.

15. The system of claim 12 , wherein the micro-lens array includes at least one non-spherical micro-lens.

16. The system of claim 12 , wherein the plurality of pixel cells are CMOS pixel cells.

17. The system of claim 12 , wherein each of the micro-lenses is formed in a substrate and comprises a lens material exhibiting a refractive index greater than that of the substrate.

18. The system of claim 12 , wherein each of the micro-lenses is formed in a substrate and comprises a lens material exhibiting a refractive index less than the substrate.

19. The system of claim 12 , wherein the imaging device further comprises a plurality of color filters respectively associated with said pixel cells and wherein the plurality of color filters includes at least a first filter for a first color and a second filter for a second color.

20. The system of claim 19 , wherein said plurality of micro-lenses includes at least a first micro-lens associated with the first filter and a second micro-lens associated with the second filter, said first and second micro-lenses each being configured to account for optical aberrations in the light directed through the first and second filters.

21. The system of claim 12 , wherein each of the micro-lenses is formed in a substrate and comprises lens material located within a recessed area of a substrate which serves as a mold for the lens material.

22. The system of claim 21 , wherein the recessed area has at least one arcuate portion.

23. The system of claim 21 , wherein the recessed area is shaped such that said lens material corrects for optical aberrations.

24. The system of claim 12 wherein the focal point of at least a second microlens is not shifted away from the center of the pixel cell associated with the second micro-lens.

25. The system of claim 12 wherein the focal point of at least a second microlens is shifted away, by a second distance, from the center of the pixel cell associated with the second micro-lens.