Angle Sensitive Pixels For Integrated Light Field Sensing

Abstract

Angle-sensitive pixels are micro-scale devices which capture information about both the intensity and incident angle of the light they see. Using pairs of local diffraction gratings above a photodiode, these pixels employ the Talbot effect to detect incident angle. The gratings are implemented with the metal interconnect layers of CMOS manufacturing technology and therefore require no post-processing or external optics. Altering layout geometries for different angle-sensitive pixels generates a distinct angular response with a characteristic frequency and orientation. To function effectively, image sensors need to employ a diverse set of angle-sensitive pixels whose responses, taken together, forms a complete basis similar to a non-separable low-order 2D Hartley transform of local incident angle. As 2D frequency-domain transforms play an important role in image processing, these devices are useful for a variety of imaging tasks. This thesis demonstrates several CMOS image sensors utilizing these devices to perform different functions, such as lensless 3D object localization, single-shot light-field capture, and optoelectronic image compression. The algorithms used for these tasks are simple and take advantage of the transform-based nature of angle-sensitive pixel based image capture.