Polarized light is a naturally occurring phenomenon that human vision does not discern, yet it can provide useful
supplementary information from an image or optical system. Polarization detection can be implemented using hybrid
sensors where additional polarizing material is mounted onto a standard sensor. However these types of sensor tend to
be expensive, requiring extra manufacturing and materials. Presented is a low cost polarization sensor which is
implemented using standard CMOS technology and manufacturing techniques, without the need for supplementary
implants or optical layers. The polarization sensor is realised using a polarization grating, formed from a standard metal
layer, above a CMOS sensor. To compensate for the loss of photons due to the polarization grating, a high dynamic
range sensor is implemented using large, 110 micron photodiodes. The photosensor is used in a "light to frequency
conversion pixel" where the photocurrent is converted to a digital square wave output with a frequency proportional to
the photon flux density. A modulation depth of 10% is achieved. A rotary encoder application implementing the
polarization sensor is discussed.
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