Integrated Polarization-Analyzing CMOS Image Sensor for Detecting the Incoming Light Ray Direction

A complementary metal-oxide-semiconductor (CMOS) image sensor used to detect the incoming light ray direction using polarization information is presented. The chip consists of an array of 128 × 128 pixels, and each pixel is embedded with a metallic wire-grid micropolarizer. It occupies an area of 5 × 4 mm², and it has been designed and fabricated in a 180-nm CMOS process. Extinction ratios of 6.3 and 7.7 were achieved in two different polarization sense regions. The Stokes parameters, which are needed to evaluate the degree of polarization (DOP) and electric-field vector intensity, are computed from the pixel with the micropolarizer oriented at 0°, 45°, and 90°. We show that the variations in the DOP and the e-vector pattern with the incoming polarized light ray direction can be used as a directional reference source for autonomous agent navigation. We also show that the measurement results of ellipticity and azimuthal angles for the incoming light ray using the Stokes parameters can allow on-chip position detection based on the angle of the incoming light ray with little complexity. A very high correlation coefficient bigger than 0.94 was obtained between the measured and theoretical incoming light ray angles.