Light field image sensor with an angle-sensitive pixel (ASP) device
An angle-sensitive pixel (ASP) device that uses the Talbot effect to detect the local intensity and incident angle of light includes a phase grating disposed above a photodiode assembly or a phase grating disposed above an analyzer grating that is disposed above a photodiode assembly. When illuminated by a plane wave, the upper grating generates a self-image at a selected Talbot depth. Several such structures, tuned to different incident angles, are sufficient to extract local incident angle and intensity. Arrays of such structures are sufficient to localize light sources in three dimensions without any additional optics.
1. An angle-sensitive pixel (ASP) device, comprising:
a substrate; and
a plurality of nano-scale to micron-scale ASPs disposed in and on the substrate, wherein each ASP comprises:
a phase grating having a period, p 1 , further wherein the phase grating is characterized by a periodic variation of refractive index in a direction transverse to an incident light field and forms a periodic intensity pattern in a Talbot plane below the phase grating;
an amplitude transmission analyzer grating having a period, p 2 disposed in the Talbot plane; and
a sensor disposed at a selected distance below the analyzer grating.
2. The ASP device of claim 1 , further comprising a dispersive material patterned over the phase grating.
3. The ASP device of claim 1 , wherein the phase grating comprises silicon dioxide.
4. The ASP device of claim 1 , wherein the sensor comprises at least one pair of periodic, interleaved N+/p-substrate diffusion diodes.
5. The device of claim 1 , wherein p 2 =p 1 .
6. The device of claim 1 , wherein the analyzer grating is disposed at a second selected Talbot distance z T2 =(m 2 /n 2 )(2p 1 2 /λ), where m, n are positive integers and p 1 is equal to or greater than λ.
7. The device of claim 1 , wherein the sensor is disposed at a first selected Talbot distance z T1 =(m 1 /n 1 )(2p 1 2 /λ), where m, n are positive integers and p1 is equal to or greater than λ.
8. The device of claim 1 , wherein the device is an integrated CMOS semiconductor structure.
9. An angle-sensitive pixel (ASP) device, comprising:
a substrate; and
a plurality of ASPs disposed in and on the substrate, wherein each ASP comprises:
a phase grating having a period, p 1 , further wherein the phase grating is characterized by a periodic variation of refractive index in a direction transverse to an incident light field and forms a periodic intensity pattern in a Talbot plane below the phase grating; and
a sensor disposed in the Talbot plane,
further wherein at least some of the plurality of the angle sensitive pixels have different orientations with respect to each other.
10. The ASP device of claim 9 , further comprising a dispersive material patterned over the phase grating.
11. The ASP device of claim 9 , wherein the phase grating comprises silicon dioxide.
12. The ASP device of claim 9 , wherein the sensor comprises at least one pair of interleaved N+/p-substrate diffusion diodes.
13. The device of claim 9 , wherein the sensor is disposed at a selected Talbot distance z T1 =(m 1 /n 1 )(2p 1 2 /λ), where m, n are positive integers and p1 is equal to or greater than λ.
14. The device of claim 9 , wherein the device is an integrated CMOS semiconductor structure.
15. A light field imaging device comprising a two-dimensional, M×N array of ASP devices according to claim 1 or 9 , where M, N are integers equal to or greater than one.