Real time extraction of polarimetric information at the focal plane

Traditional imaging systems focus on converting light's intensity and color property into suitable electronic signals. An important property of light, polarization is ignored with these traditional imaging systems. Polarization vision contains information about the imaged environment, such as surface shapes, curvature and material properties. Real time extraction of polarization properties would further allow synergy with traditional adaptive spatiotemporal image processing techniques for synthetic imaging. Therefore, we have developed an image sensor with real-time polarimetric extraction capability at the focal plane using low power analog circuits. This novel imaging system is the first of its kind to compute Stokes parameters at the focal plane in real-time. In order to fully describe the polarization state of light in nature, three linear polarized projections or two linear polarized projections in combination with the total intensity are required. We have fabricated a two layer micro polarizer array with total thickness of around 20μm. The micro polarizer array is mounted on top of the imaging sensor. The image sensor is composed of a 256 by 256 photo pixel array, noise suppression circuitry and analog processing circuitry for polarimetric computation. The image sensor was fabricated in 0.18μ process with 10μm pixel pitch and 75% fill factor. Block-parallel pixel read out is employed in order to compute Stokes parameters on a neighborhood of 2 by 2 pixels. The Stokes parameters are presented together with the noise suppressed intensity image. Experimental data from the polarimetric imaging system is also presented.