Imaging module with symmetrical lens system and method of manufacture
View Patent ↗An imaging module and method of fabrication. The method comprises forming a first lens wafer with a plurality of outer negative lenses and forming a second lens wafer with a plurality of inner negative lenses The method further comprises bonding the first lens wafer and second lens wafer to create a bonded stack; forming a plurality of inner positive lenses on the second lens wafer and bonding a spacer wafer to the second lens wafer; and forming a plurality of outer positive lenses on the first lens wafer.
1. An imaging module comprising:
a first transparent substrate having a first aperture layer on a first side and a second aperture layer on a second side, the first aperture layer comprising a first aperture and the second aperture layer comprising a second aperture such that the first aperture and the second aperture are optically aligned;
a first lens replication layer comprising a first positive lens on a first side of the first transparent substrate, the first aperture layer being between the first lens replication layer and the first side of the first transparent substrate and the first positive lens being optically aligned with the first aperture;
a second lens replication layer comprising a first negative lens on a second side of the first transparent substrate, the second aperture layer being between a first side of the second lens replication layer and the second side of the first transparent substrate and the first negative lens being optically aligned with the second aperture;
a second transparent substrate having a third aperture layer on a first side and a fourth aperture layer on a second side, the third aperture layer comprising a third aperture and the fourth aperture layer comprising a fourth aperture such that the third aperture and the fourth aperture are optically aligned;
a third lens replication layer comprising a second negative lens on a first side of the second transparent substrate, the third aperture layer being between a first side of the third lens replication layer and the first side of the second transparent substrate and the second negative lens being optically aligned with the third aperture;
a fourth lens replication layer comprising a second positive lens on a second side of the second transparent substrate, the fourth aperture layer being between the fourth lens replication layer and the second side of the second transparent substrate and the second positive lens being optically aligned with the fourth aperture; and
an image sensor comprising a pixel array optically aligned with said lenses and apertures,
wherein a second side of the second lens replication layer is attached to a second side of the third lens replication layer such that the first, second, third and fourth apertures are optically aligned.
2. The imaging module of claim 1 , further comprising an encapsulating material on each side of the imaging module.
3. The imaging module of claim 2 , further comprising a spacer between the fourth lens replication layer and the through-wafer interconnect substrate layer.
4. The imaging module of claim 2 , further comprising solder balls connected to the image sensor through the through-wafer interconnect substrate layer.
5. The imaging module of claim 1 , further comprising a through-wafer interconnect substrate holding the image sensor.
6. The imaging module of claim 1 , wherein the lens replication layers comprise an ultraviolet-curable hybrid polymer.
7. The imaging module of claim 1 , wherein the aperture layers comprise a light-absorbing material.
8. The imaging module of claim 1 , further comprising a lens hood affixed to an image receiving side of the imaging module.
9. The imaging module of claim 1 , wherein the first and second transparent substrates comprise a boro-float glass.
10. The imaging module of claim 9 , wherein the boro-float glass has a coefficient of thermal expansion between 2 and 5.
11. The imaging module of claim 1 , further comprising an infrared cut filter.
12. The imaging module of claim 1 , wherein the second aperture is a system stop and the first, third and fourth apertures are field stops.
13. The imaging module of claim 1 , wherein at least one of the first positive lens, first negative lens, second negative lens and second positive lens have 6th order aspheric coefficients.
14. The imaging module of claim 1 , wherein at least one of the first positive lens, first negative lens, second negative lens and second positive lens has an Abbe number greater than 50.
15. The imaging module of claim 1 , wherein at least one of the first positive lens and second positive lens have an Abbe number greater than 50 and the first negative lens and second negative lens have an Abbe number less than 50.