Method of forming an imaging device
A method, apparatus, and system that provides a holographic layer as a micro-lens array and/or a color filter array in an imager. The method of writing the holographic layer results in overlapping areas in the hologram for corresponding adjacent pixels in the imager which increases collection of light at the pixels, thereby increasing quantum efficiency.
1. A method of recording an optical holographic layer in an imaging device, comprising:
projecting an object beam into an optical system;
projecting a reference beam into the optical system;
producing interference between the reference beam and the object beam to create interference beams of light; and
projecting the interference beams onto the holographic layer to form holographic patterns to focus and color separate input radiation onto photosensors of pixels in a pixel array.
2. The method of claim 1 , further comprising emanating the object beam and the reference beam from coherent light sources.
3. The method of claim 1 , further comprising emanating the object beam from an object light source, said object light source further comprising a plurality of point sources arranged substantially to correspond to the pixels in the array.
4. The method of claim 3 , wherein the plurality of point sources comprises monochromatic light sources.
5. The method of claim 1 , wherein the optical system comprises an optical lens.
6. The method of claim 1 , wherein the optical system comprises a concave semitransparent mirror.
7. The method of claim 1 , wherein the holographic patterns comprise diffraction gratings.
8. The method of claim 1 , further comprising projecting the object beam through a second optical system comprising lenses for projecting refracted beams of the object beam to the optical system.
9. The method of claim 1 , further comprising projecting the interference beams through respective elliptical areas of the holographic layer.
10. The method of claim 9 , wherein the respective elliptical areas overlap.
11. The method of claim 1 , further comprising projecting the interference beams through respective conical areas of the holographic layer.
12. A method of forming an imaging device, said method comprising:
providing a pixel array comprising a plurality of pixels formed in a substrate and a holographic material formed over the substrate;
projecting object beams and reference beams into an optical system to create interference beams of light; and
projecting the interference beams onto the holographic material to form holographic patterns corresponding to the pixels in the pixel array, wherein a respective holographic pattern is configured to focus and color separate input radiation onto a respective pixel of said pixel array.
13. The method of claim 12 , wherein the object beams comprise a plurality of beams corresponding to respective pixels in the pixel array.
14. The method of claim 13 , further comprising projecting the object beams into the optical system simultaneously.
15. The method of claim 13 , further comprising projecting the object beams into the optical system sequentially.
16. The method of claim 12 , wherein the object beams comprise a plurality of monochromatic light beams.
17. The method of claim 12 , wherein the optical system comprises an optical lens.
18. The method of claim 12 , wherein the optical system comprises a concave semitransparent mirror.
19. The method of claim 12 , wherein the holographic patterns comprise diffraction gratings.
20. The method of claim 12 , further comprising projecting the object beam through a second optical system comprising lenses for projecting refracted beams of the object beam to the optical system.
21. The method of claim 12 , wherein the pixel array further comprises at least one layer of material between the substrate and the holographic material.
22. The method of claim 12 , wherein the respective holographic patterns are configured to filter input radiation according to a color associated with the corresponding pixel.
23. The method of claim 22 , wherein the pixel array comprises a plurality of pixels arranged in a Bayer color pattern.