Light field image sensor, method and applications
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. A method for extracting incident light-angle information from a light source object, comprising:
providing a two-dimensional, M×N sensor array of ASP-light-field detectors, where M, N are integers equal to or greater than one, wherein the array of ASP-light-field detectors includes:
a plurality of nano-scale to micron-scale ASPs disposed in and on a substrate, wherein each ASP comprises:
a phase grating having a period, p1, 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, p2 disposed in the Talbot plane; and
a sensor disposed at a selected distance below the analyzer grating;
positioning the sensor array adjacent the light source object; and
determining the light source object's location in three-dimensional space based upon light from the object that is incident on the sensor array.
2. The method of claim 1 , wherein the light source object comprises a plurality of fluorescent cells in a tissue.
3. The method of claim 2 , further comprising detecting the location of individual fluorescent cells by triangulating back from the incident light angles detected by each sensor in the array.
4. The method of claim 2 , further comprising detecting a change in the fluorescence of an individual fluorescent cell independent of another of the fluorescent cells by triangulating back from the incident light angles detected by each sensor in the array.
5. The method of claim 1 , wherein each of the plurality of ASPs is a lensless ASP.
6. The method of claim 5 , comprising extracting the incident light-angle information from the light source object without the use of a lens.
7. A method for determining a location of a distant object, comprising:
providing an ASP sensor array according to claim 5 ;
providing a lens system having a focal plane, in an object space adjacent the ASP sensor array; and
detecting one of a divergence and a convergence of light from the object that is incident on the ASP sensor array.
8. The method of claim 7 , wherein the distant object comprises a plurality of light-emitting objects.
9. The method of claim 1 , further comprising providing a color filter in or on the ASP sensor array.
10. The method of claim 9 , wherein each ASP comprises a plurality of color filter layers.
11. The method of claim 10 , wherein each ASP further comprises a respective plurality of color-tuned diffraction gratings, whereby color imaging is enabled.