Low-cost encoder using a phase shifting algorithm utilizing polarization properties of light

In this work a novel polyphase optical encoder is presented, which uses a mathematical algorithm to take advantage of the polarization properties of light. This optical encoder has excellent accuracy, precision, and resolution in measuring the angular position of a shaft. Furthermore, it is designed to work with low-cost optical components. Initially, a light beam passes through a rotating polarizer, and readings are obtained from low-cost photoresistors located under phase shifted analyzers to generate characteristic curves for each of the phases, in the plane formed by the measured angle and the intensity of light. These curves are correlated to the ideal polarization curve formed by Malus' law via polynomial expressions to obtain the relationship between actual values and the ideal square cosine. After this characterization process, the encoder is ready for indefinite use, and operational data are introduced to a phase shifting algorithm, to obtain the angle position of any rotating device.