Method and apparatus for balancing color response of imagers
A micro-lens array with reduced or no empty space between individual micro-lenses and a method for forming same. The micro-lens array is formed by patterning a first set of micro-lens material in a checkerboard pattern on a substrate. The first set of micro-lens material is reflowed and cured into first micro-lenses impervious to subsequent reflows. Then, a second set of micro-lens material is patterned in spaces among the first micro-lenses, reflowed and cured into second micro-lenses. The reflows and cures can be conducted under different conditions, and the micro-lenses may be differently sized. The conditions of the reflows can be chosen to ensure that the focal lengths of micro-lenses are optimized for maximum sensor signal.
1. A micro-lens array, comprising:
a first set of micro-lenses comprising a plurality of first micro-lenses each having a first size and corresponding to a first color; and
a second set of micro-lenses comprising a plurality of second micro-lenses each having a second size and corresponding to a second color,
wherein at least one of said plurality of first micro-lenses at least abuts without overlapping at least one of said plurality of second micro-lenses,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first and second sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
2. The micro-lens array of claim 1 , further comprising a third set of micro-lenses comprising a plurality of third micro-lenses each having a third size and corresponding to a third color, said third set of micro-lenses being regularly distributed throughout said micro-lens array in accordance with said predetermined color pattern.
3. The micro-lens array of claim 2 , wherein said first, second, and third sizes are equal to each other.
4. The micro-lens array of claim 1 , wherein a focal length of each of said plurality of first micro-lenses is approximately equal to a focal length of each of said plurality of second micro-lenses.
5. The micro-lens array of claim 1 , wherein a focal length of each of said plurality of first micro-lenses corresponds to a first wavelength of light, and wherein a focal length of each of said plurality of second micro-lenses corresponds to a second wavelength of light.
6. The micro-lens array of claim 1 , wherein said predetermined color pattern comprises a Bayer pattern.
7. A micro-lens array, comprising:
a first set of micro-lenses comprising a plurality of first micro-lenses;
a second set of micro-lenses comprising a plurality of second micro-lenses; and
a third set of micro-lenses comprising a plurality of third micro-lenses,
wherein said first micro-lenses at least abut without overlapping said second and third micro-lenses,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first, second, and third sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
8. The micro-lens array of claim 7 , wherein said first micro-lenses have a first size and said second micro-lenses have a second size, said second size being no smaller than said first size.
9. The micro-lens array of claim 7 , wherein said first, second, and third micro-lenses each have approximately a same focal length.
10. The micro-lens array of claim 7 , wherein a focal length of each of said plurality of first micro-lenses corresponds to a first wavelength of light, wherein a focal length of each of said plurality of second micro-lenses corresponds to a second wavelength of light, and wherein a focal length of each of said plurality of third micro-lenses corresponds to a third wavelength of light.
11. The micro-lens array of claim 7 , wherein said first, second and third sizes are equal to each other.
12. The micro-lens array of claim 7 , wherein said predetermined color pattern comprises a Bayer pattern.
13. A micro-lens array, comprising:
a first set of micro-lenses comprising a plurality of first micro-lenses; and
a second set of micro-lenses comprising a plurality of second micro-lenses,
wherein said first micro-lenses exhibit different optical transmission properties than said second micro-lenses,
wherein said first micro-lenses abut said second micro-lenses without overlapping,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first and second sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
14. The micro-lens array of claim 13 , comprising a third set of micro-lenses comprising a plurality of third micro-lenses, said third set of micro-lenses being regularly distributed throughout said micro-lens array in accordance with said predetermined color pattern.
15. The micro-lens array of claim 14 , wherein said third micro-lenses exhibit different optical transmission properties than at least one of said first and second micro-lenses.
16. The micro-lens array of claim 15 , wherein said third micro-lenses exhibit different optical transmission properties than both said first and second micro-lenses.
17. The micro-lens array of claim 14 , wherein said first micro-lenses abut said second and third micro-lenses.
18. The micro-lens array of claim 13 , wherein said predetermined color pattern comprises a Bayer pattern.
19. A semiconductor imager, comprising:
a pixel array having embedded pixel cells, each with a photosensor; and a micro-lens array, comprising:
a first set of micro-lenses comprising a plurality of first micro-lenses each having a first size; and
a second set of micro-lenses comprising a plurality of second micro-lenses each having a second size,
wherein the micro-lens array is substantially space-less between at least one of said plurality of first micro-lenses and at least one of said plurality of second micro-lenses,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first and second sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
20. The semiconductor imager of claim 19 , wherein said first size is different than said second size such that pixel cells corresponding to said second micro-lenses receive a greater amount of light than pixel cells corresponding to said first micro-lenses.
21. The semiconductor imager of claim 20 , wherein said first micro-lenses correspond to green pixel cells, and wherein said second micro-lenses correspond to red and/or blue pixel cells.
22. The semiconductor imager of claim 19 , wherein said micro-lens array further comprises a third set of micro-lenses comprising a plurality of third micro-lenses each having a third size, said third set of micro-lenses being regularly distributed throughout said micro-lens array in accordance with said predetermined color pattern.
23. The semiconductor imager of claim 22 , wherein the micro-lens array is substantially space-less between said pluralities of first, second, and third micro-lenses.
24. The semiconductor imager of claim 22 , wherein a focal length of each of said plurality of first micro-lenses is equal to a focal length of each of said plurality of second micro-lenses and a focal length of each of said plurality of third micro-lenses.
25. The semiconductor imager of claim 22 , wherein focal lengths of each of the pluralities of first, second, and third micro-lenses are adjusted for a specific color signal.
26. The semiconductor imager of claim 19 , wherein said predetermined color pattern comprises a Bayer pattern.
27. A semiconductor imager, comprising:
a substrate having pixel cells formed thereon, each with a photosensor; and
a micro-lens array for presenting an image for said pixel cells, said micro-lens array comprising:
a first plurality of first micro-lenses each having a first size; and
a second plurality of second micro-lenses each having a second size larger than said first size,
wherein said second micro-lenses are adapted to collect a greater amount of light than said first micro-lenses,
wherein at least one of said second micro-lenses abuts without overlapping at least one of said first micro-lenses,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first and second sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
28. The semiconductor imager of claim 27 , wherein said first and said second micro-lenses each exhibit a similar focal length.
29. The semiconductor imager of claim 28 , wherein said focal length extends to said photosensors.
30. The semiconductor imager of claim 27 , wherein a focal length of the plurality of first micro-lenses is adjusted for a first color signal, and wherein a focal length of the plurality of second micro-lenses is adjusted for a second color signal.
31. The semiconductor imager of claim 27 , further comprising a color filter array positioned over said pixel cells.
32. The semiconductor imager of claim 31 , wherein said color filter array is positioned between said micro-lens array and said substrate.
33. The semiconductor imager of claim 27 , further comprising a light shield positioned between said micro-lens array and said substrate.
34. The semiconductor imager of claim 27 , wherein said micro-lens array further comprises a third plurality of third micro-lenses each having a third size, said third set of micro-lenses being regularly distributed throughout said micro-lens array in accordance with said predetermined color pattern.
35. The semiconductor imager of claim 34 , wherein said first and third sizes are equal.
36. The semiconductor imager of claim 34 , wherein at least one of said first micro-lenses abuts at least one of said second micro-lenses and at least one of said third micro-lenses.
37. The semiconductor imager of claim 34 , wherein said second and third sizes are equal.
38. The semiconductor imager of claim 27 , wherein said predetermined color pattern comprises a Bayer pattern.
39. A semiconductor imager, comprising:
a substrate having pixel cells formed thereon, each with a photosensor; and
a micro-lens array for presenting an image for said pixel cells, said micro-lens array comprising:
a first set of micro-lenses comprising a plurality of first micro-lenses each having a first size; and
a second set of micro-lenses comprising a plurality of second micro-lenses each having a second size no smaller than said first size,
wherein said second micro-lenses are each positioned in a space between adjacent said first micro-lenses such that said second micro-lenses contact without overlapping said first micro-lenses,
wherein a number of said plurality of first micro-lenses is greater than a number of said plurality of second micro-lenses, and
wherein said first and second sets of micro-lenses are regularly distributed throughout said micro-lens array in accordance with a predetermined color pattern for image capture.
40. The semiconductor imager of claim 39 , further comprising a color filter array positioned over said pixel cells.
41. The semiconductor imager of claim 40 , wherein said color filter array is positioned between said micro-lens array and said substrate.
42. The semiconductor imager of claim 39 , wherein said second size is larger than said first size.
43. The semiconductor imager of claim 39 , wherein said first and said second micro-lenses each exhibit a similar focal length.
44. The semiconductor imager of claim 43 , wherein said focal length extends to said photosensors.
45. The semiconductor imager of claim 39 , wherein a focal length of the plurality of first micro-lenses is adjusted for a first color signal, and wherein a focal length of the plurality of second micro-lenses is adjusted for a second color signal.
46. The semiconductor imager of claim 39 , wherein said micro-lens array further comprises a third plurality of third micro-lenses each having a third size, said third set of micro-lenses being regularly distributed throughout said micro-lens array in accordance with said predetermined color pattern.
47. The semiconductor imager of claim 46 , wherein said first, second, and third sizes are equal.
48. The semiconductor imager of claim 39 , wherein said predetermined color pattern comprises a Bayer pattern.