Image sensor with optical filters having alternating polarization for 3D imaging

1. An image sensor comprising:

a beamsplitter to encode incident light with a set of two orthogonal polarizations including a first polarization and a second polarization, wherein the incident light includes light polarized to the first polarization corresponding to a first view of a three-dimensional object and light polarized to the second polarization corresponding to a second view of the three-dimensional object;

a pixel array comprising a plurality of pixel units arranged in rows and columns, each pixel unit including at least one imaging pixel;

a polarizer array optically coupled to the pixel array to filter the incident light, the polarizer array comprising a plurality of polarizing filters wherein each pixel unit in the pixel array is optically coupled to a corresponding polarizing filter in the polarizer array, and wherein the polarizations of all polarizing filters in the polarizer array are selected from the set of two orthogonal polarizations consisting of the first polarization and the second polarization;

wherein each imaging pixel comprises:

a photosensing region disposed in a semiconductor layer of the image sensor;

a color filter disposed on the light-incident side of the image sensor; and

a microlens disposed on the light incident side to focus incident light to the photosensing region.

2. The image sensor of claim 1 wherein the polarizations of the polarizing filters in every row and every column of the polarizer array alternate between the first polarization and the second polarization.

3. The image sensor of claim 1 wherein rows in the polarizing array alternate between rows in which all polarizing filters have the first polarization and rows in which all polarizing filters have the second polarization.

4. The image sensor of claim 1 wherein columns in the polarizing array alternate between columns in which all polarizing filters have the first polarization and columns in which all polarizing filters have the second polarization.

5. The image sensor of claim 1 wherein the polarizing filter corresponding to each imaging pixel is disposed between the color filter and the microlens.

6. The image sensor of claim 1 wherein the color filter is part of a color filter array in which the color filters are arranged in a Bayer pattern.

7. The image sensor of claim 1 wherein each imaging pixel further comprises a planarization layer disposed on the microlens, and wherein the polarizing filter corresponding to each imaging pixel is disposed on the planarization layer.

8. The image sensor of claim 1 wherein the image sensor is a complementary metal-oxide-semiconductor (“CMOS”) image sensor.

9. An imaging system for three-dimensional (“3D”) imaging, the system comprising:

a first channel for generating a first view of a 3D object;

a second channel for generating a second view of the 3D object;

a beam splitter coupled to the first and second channels to combine the first and second views to output polarization-encoded light having a first polarization corresponding to the first view of the 3D object and a second polarization corresponding to the second view of the 3D object; and

an image sensor coupled to receive the polarization-encoded light, the image sensor including:

a pixel array comprising a plurality of pixel units arranged in rows and columns, each pixel unit including four imaging pixels arranged into a Bayer pattern; and

a polarizer array optically coupled to the pixel array to filter the polarization-encoded light, the polarizer array comprising a plurality of polarizing filters wherein each pixel unit in the pixel array is optically coupled to a corresponding polarizing filter in the polarizer array, and wherein the polarizations of all polarizing filters in the polarizer array are selected from a set of two orthogonal polarizations consisting of the first polarization and the second polarization;

wherein each imaging pixel comprises:

a photosensing region disposed in a semiconductor layer of the image sensor;

a color filter disposed on the light-incident side of the image sensor; and

a microlens disposed on the light incident side to focus incident light to the photosensing region.

10. The imaging system of claim 9 wherein the first and second channels generate non-polarized views of the 3D object and wherein the beam splitter is a polarizing beam splitter configured to combine and polarize the first and second views with the first and second polarizations, respectively, to generate the polarization-encoded light.

11. The imaging system of claim 9 wherein the first channel includes a first polarizer coupled to polarize the first view of the 3D object with the first polarization, the second channel includes a second polarizer coupled to polarize the second view with the second polarization, and wherein the beam splitter is a non-polarizing beam splitter.

12. The imaging system of claim 9 wherein the polarizations of the polarizing filters in every row and every column of the polarizer array alternate between the first polarization and the second polarization.

13. The imaging system of claim 9 wherein rows in the polarizing array alternate between rows in which all polarizing filters have the first polarization and rows in which all polarizing filters have the second polarization.

14. The imaging system of claim 9 wherein columns in the polarizing array alternate between columns in which all polarizing filters have the first polarization and columns in which all polarizing filters have the second polarization.

15. The imaging system of claim 9 wherein the polarization-encoded light includes light polarized to the first polarization corresponding to a first view of a three-dimensional object and light polarized to the second polarization corresponding to a second view of the three-dimensional object.

16. The imaging system of claim 9 wherein the polarizing filter corresponding to each imaging pixel is disposed between the color filter and the microlens.

17. The imaging system of claim 9 wherein each imaging pixel further comprises a planarization layer disposed on the microlens, and wherein the polarizing filter corresponding to each imaging pixel is disposed on the planarization layer.

18. The imaging system of claim 9 wherein the image sensor is a complementary metal-oxide-semiconductor (“CMOS”) image sensor.