Metrological errors in optical encoders

Optical encoders are commonly used for high accuracy position measurement, both linear and angular. In order to determine the position, the optical encoder generates two electrical signals that are combined using the arctangent algorithm. There are a number of situations, optical, mechanical and electronic, that affect these signals and produce an error in the position measurement. In this work, we analyze the error produced in optical encoders when the electrical signals vary from their nominal values. By using a linear expansion, simple expressions for the error estimation are obtained which can be used to improve the design of the optical encoders. In addition, an experimental verification of the theoretical results is performed.