Depth estimating image capture device

1. A depth estimating image capture device comprising:

a light-transmitting section that is made up of a plurality of portions, each including a diffraction region that diffracts incoming light, a transparent region that transmits the incoming light without diffracting the light, and a polarization region arranged so as to overlap at least partially with the diffraction region;

an image sensor in which a plurality of unit elements are arranged two-dimensionally on an imaging area, wherein each of the unit elements includes a first photosensitive cell, a second photosensitive cell, and a polarization filter arranged so as to face the first photosensitive cell;

an imaging section configured to obtain images produced on the imaging area by the light transmitted through the transparent region and by the light transmitted through the diffraction region; and

a signal processing section that processes a signal supplied from the image sensor.

2. The depth estimating image capture device of claim 1 , wherein if the unit elements are arranged on the imaging area in x and y directions,

the diffraction region is configured to generate mainly an n th -order diffracted light ray (where n is an integer that is equal to or greater than one) and to make the n th -order diffracted light ray incident at a point on the imaging area that has shifted in either the x direction or the y direction with respect to the point of incidence of the light that has been transmitted through the transparent region.

3. The depth estimating image capture device of claim 2 , wherein if the diffraction region, the polarization region and the polarization filter are called a first diffraction region, a first polarization region and a first polarization filter, respectively,

each of the plurality of portions of the light-transmitting section further includes a second diffraction region that generates mainly an n th -order diffracted light ray and a second polarization region that is arranged so as to overlap at least partially with the second diffraction region and that has a different polarization transmission axis direction from the first polarization region, and

each said unit element of the image sensor further includes a third photosensitive cell, and a second polarization filter that is arranged to face the third photosensitive cell and that has a different polarization transmission axis direction from the first polarization filter.

4. The depth estimating image capture device of claim 3 , wherein the first and second diffraction regions are configured so that the n th -order diffracted light rays that have gone out of the first and second diffraction regions are incident on the imaging area at respective points that are symmetric to a point of incidence of the light that has been transmitted through the transparent region.

5. The depth estimating image capture device of claim 1 , wherein the diffraction region is configured to generate a zero-order diffracted light ray and ±n th -order diffracted light rays (where n is an integer that is equal to or greater than one), and

wherein the polarization region includes a first polarization region that is arranged on the path of the +n th -order diffracted light ray and a second polarization region that is arranged on the path of the −n th -order diffracted light ray and that has a different polarization transmission axis direction from the first polarization region, and

wherein each said unit element of the image sensor further includes a third photosensitive cell and a third polarization filter that is arranged to face the third photosensitive cell and that has a different polarization transmission axis direction from the first polarization filter.

6. The depth estimating image capture device of claim 3 , wherein the polarization transmission axis direction of one of the first and second polarization regions is the same as the polarization transmission axis direction of one of the first and second polarization filters.

7. The depth estimating image capture device of claim 3 , wherein the polarization transmission axis direction of the first polarization region intersects with the polarization transmission axis direction of the second polarization region at right angles, and

wherein the polarization transmission axis direction of the first polarization filter intersects with the polarization transmission axis direction of the second polarization filter at right angles.

8. The depth estimating image capture device of claim 1 , wherein the signal processing section includes an image processing section that obtains, based on respective output signals of the first and second photosensitive cells, a first image generated by the light that has been transmitted through the diffraction region and a second image generated by the light that has been transmitted through the transparent region.

9. The depth estimating image capture device of claim 6 , wherein the image processing section generates information about the subject's depth based on the magnitude of shift between the respective positions of the subject on the first and second images.

10. The depth estimating image capture device of claim 3 , wherein the signal processing section includes an image processing section that obtains, based on first, second and third signals supplied from the first, second and third photosensitive cells, respectively, first, second and third images generated by the light transmitted through the first diffraction region, the light transmitted through the second diffraction region, and the light transmitted through the transparent region, respectively.

11. The depth estimating image capture device of claim 8 , wherein the image processing section generates information about the subject's depth based on the magnitude of shift between the positions of the subject on the first and third images and on the magnitude of shift between the positions of the subject on the second and third images.