Absolute interferometric angle measurement

A new method of absolute angle measurement based on analysis of interference fringe patterns is proposed. This approach is a bridge between interferometry, offering high accuracy, and other methods that are using position sensors or amplitude effects, which can give information about absolute value of angle. Utilisation of quadrature signals makes it possible to achieve better stability, with comparison to some other methods, thanks to reduced influence of thermal expandability. Usage of special signal processing algorithms facilitates wide measurement range and high resolution. Simulations and experiments show the possibility of achieving the range of 1 deg with arc-sec accuracy. Using commercially available optical and electronic components makes it possible to create lightweight, battery operated device that could be applied in CNC machine alignment process.